Fixes the following GCC 5 warnings:
```
core/object.h:193:11: warning: 'MethodInfo::flags' will be initialized after [-Wreorder]
core/object.h:192:15: warning: 'PropertyInfo MethodInfo::return_val' [-Wreorder]
core/object.cpp:278:1: warning: when initialized here [-Wreorder]
core/script_debugger_remote.h:97:6: warning: 'ScriptDebuggerRemote::max_cps' will be initialized after [-Wreorder]
core/script_debugger_remote.h:91:6: warning: 'int ScriptDebuggerRemote::max_messages_per_frame' [-Wreorder]
core/script_debugger_remote.cpp:1086:1: warning: when initialized here [-Wreorder]
core/script_debugger_remote.h:98:6: warning: 'ScriptDebuggerRemote::char_count' will be initialized after [-Wreorder]
core/script_debugger_remote.h:92:6: warning: 'int ScriptDebuggerRemote::n_messages_dropped' [-Wreorder]
core/script_debugger_remote.cpp:1086:1: warning: when initialized here [-Wreorder]
modules/bullet/area_bullet.h:102:7: warning: 'AreaBullet::isScratched' will be initialized after [-Wreorder]
modules/bullet/area_bullet.h:92:39: warning: 'PhysicsServer::AreaSpaceOverrideMode AreaBullet::spOv_mode' [-Wreorder]
modules/bullet/area_bullet.cpp:46:1: warning: when initialized here [-Wreorder]
modules/bullet/collision_object_bullet.h:127:15: warning: 'CollisionObjectBullet::space' will be initialized after [-Wreorder]
modules/bullet/collision_object_bullet.h:117:7: warning: 'CollisionObjectBullet::Type CollisionObjectBullet::type' [-Wreorder]
modules/bullet/collision_object_bullet.cpp:67:1: warning: when initialized here [-Wreorder]
modules/bullet/godot_ray_world_algorithm.h:48:7: warning: 'GodotRayWorldAlgorithm::m_ownManifol1d' will be initialized after [-Wreorder]
modules/bullet/godot_ray_world_algorithm.h:46:33: warning: 'const btDiscreteDynamicsWorld* GodotRayWorldAlgorithm::m_world' [-Wreorder]
modules/bullet/godot_ray_world_algorithm.cpp:50:1: warning: when initialized here [-Wreorder]
modules/bullet/godot_result_callbacks.h:91:18: warning: 'GodotAllConvexResultCallback::m_exclude' will be initialized after [-Wreorder]
modules/bullet/godot_result_callbacks.h:89:6: warning: 'int GodotAllConvexResultCallback::m_resultMax' [-Wreorder]
modules/bullet/godot_result_callbacks.h:93:2: warning: when initialized here [-Wreorder]
modules/bullet/godot_result_callbacks.h:142:18: warning: 'GodotAllContactResultCallback::m_exclude' will be initialized after [-Wreorder]
modules/bullet/godot_result_callbacks.h:140:6: warning: 'int GodotAllContactResultCallback::m_resultMax' [-Wreorder]
modules/bullet/godot_result_callbacks.h:147:2: warning: when initialized here [-Wreorder]
modules/bullet/godot_result_callbacks.h:168:18: warning: 'GodotContactPairContactResultCallback::m_exclude' will be initialized after [-Wreorder]
modules/bullet/godot_result_callbacks.h:166:6: warning: 'int GodotContactPairContactResultCallback::m_resultMax' [-Wreorder]
modules/bullet/godot_result_callbacks.h:173:2: warning: when initialized here [-Wreorder]
modules/bullet/godot_result_callbacks.h:195:18: warning: 'GodotRestInfoContactResultCallback::m_exclude' will be initialized after [-Wreorder]
modules/bullet/godot_result_callbacks.h:191:7: warning: 'bool GodotRestInfoContactResultCallback::m_collided' [-Wreorder]
modules/bullet/godot_result_callbacks.h:199:2: warning: when initialized here [-Wreorder]
modules/bullet/rigid_body_bullet.h:200:9: warning: 'RigidBodyBullet::gravity_scale' will be initialized after [-Wreorder]
modules/bullet/rigid_body_bullet.h:199:9: warning: 'real_t RigidBodyBullet::mass' [-Wreorder]
modules/bullet/rigid_body_bullet.cpp:258:1: warning: when initialized here [-Wreorder]
modules/bullet/rigid_body_bullet.h:222:28: warning: 'RigidBodyBullet::force_integration_callback' will be initialized after [-Wreorder]
modules/bullet/rigid_body_bullet.h:219:7: warning: 'bool RigidBodyBullet::isTransformChanged' [-Wreorder]
modules/bullet/rigid_body_bullet.cpp:258:1: warning: when initialized here [-Wreorder]
modules/bullet/rigid_body_bullet.h:220:7: warning: 'RigidBodyBullet::previousActiveState' will be initialized after [-Wreorder]
modules/bullet/rigid_body_bullet.h:208:6: warning: 'int RigidBodyBullet::maxCollisionsDetection' [-Wreorder]
modules/bullet/rigid_body_bullet.cpp:258:1: warning: when initialized here [-Wreorder]
modules/bullet/soft_body_bullet.h:69:9: warning: 'SoftBodyBullet::total_mass' will be initialized after [-Wreorder]
modules/bullet/soft_body_bullet.h:68:6: warning: 'int SoftBodyBullet::simulation_precision' [-Wreorder]
modules/bullet/soft_body_bullet.cpp:38:1: warning: when initialized here [-Wreorder]
modules/bullet/soft_body_bullet.h:76:9: warning: 'SoftBodyBullet::drag_coefficient' will be initialized after [-Wreorder]
modules/bullet/soft_body_bullet.h:61:14: warning: 'btSoftBody* SoftBodyBullet::bt_soft_body' [-Wreorder]
modules/bullet/soft_body_bullet.cpp:38:1: warning: when initialized here [-Wreorder]
modules/bullet/space_bullet.h:97:22: warning: 'SpaceBullet::solver' will be initialized after [-Wreorder]
modules/bullet/space_bullet.h:95:35: warning: 'btDefaultCollisionConfiguration* SpaceBullet::collisionConfiguration' [-Wreorder]
modules/bullet/space_bullet.cpp:333:1: warning: when initialized here [-Wreorder]
modules/bullet/space_bullet.h:101:23: warning: 'SpaceBullet::soft_body_world_info' will be initialized after [-Wreorder]
modules/bullet/space_bullet.h:99:23: warning: 'btGhostPairCallback* SpaceBullet::ghostPairCallback' [-Wreorder]
modules/bullet/space_bullet.cpp:333:1: warning: when initialized here [-Wreorder]
modules/gdnative/nativescript/nativescript.h:79:13: warning: 'NativeScriptDesc::base_native_type' will be initialized after [-Wreorder]
modules/gdnative/nativescript/nativescript.h:73:9: warning: 'String NativeScriptDesc::documentation' [-Wreorder]
modules/gdnative/nativescript/nativescript.h:88:9: warning: when initialized here [-Wreorder]
modules/gdscript/gdscript.h:296:6: warning: 'GDScriptWarning::line' will be initialized after [-Wreorder]
modules/gdscript/gdscript.h:294:4: warning: 'GDScriptWarning::Code GDScriptWarning::code' [-Wreorder]
modules/gdscript/gdscript.h:303:2: warning: when initialized here [-Wreorder]
scene/3d/physics_body.h:544:7: warning: 'PhysicalBone::simulate_physics' will be initialized after [-Wreorder]
scene/3d/physics_body.h:543:7: warning: 'bool PhysicalBone::_internal_static_body' [-Wreorder]
scene/3d/physics_body.cpp:2502:1: warning: when initialized here [-Wreorder]
scene/3d/physics_body.h:546:6: warning: 'PhysicalBone::bone_id' will be initialized after [-Wreorder]
scene/3d/physics_body.h:539:12: warning: 'Skeleton* PhysicalBone::parent_skeleton' [-Wreorder]
scene/3d/physics_body.cpp:2502:1: warning: when initialized here [-Wreorder]
scene/3d/spring_arm.h:44:11: warning: 'SpringArm::mask' will be initialized after [-Wreorder]
scene/3d/spring_arm.h:43:8: warning: 'float SpringArm::current_spring_length' [-Wreorder]
scene/3d/spring_arm.cpp:37:1: warning: when initialized here [-Wreorder]
scene/animation/skeleton_ik.h:159:11: warning: 'SkeletonIK::target_node_override' will be initialized after [-Wreorder]
scene/animation/skeleton_ik.h:152:7: warning: 'bool SkeletonIK::use_magnet' [-Wreorder]
scene/animation/skeleton_ik.cpp:418:1: warning: when initialized here [-Wreorder]
scene/resources/tile_set.h:84:9: warning: 'TileSet::AutotileData::size' will be initialized after [-Wreorder]
scene/resources/tile_set.h:83:7: warning: 'int TileSet::AutotileData::spacing' [-Wreorder]
scene/resources/tile_set.h:92:12: warning: when initialized here [-Wreorder]
scene/resources/tile_set.h:115:12: warning: 'TileSet::TileData::tile_mode' will be initialized after [-Wreorder]
scene/resources/tile_set.h:114:9: warning: 'Color TileSet::TileData::modulate' [-Wreorder]
scene/resources/tile_set.h:120:12: warning: when initialized here [-Wreorder]
servers/physics/body_sw.h:84:19: warning: 'BodySW::direct_state_query_list' will be initialized after [-Wreorder]
servers/physics/body_sw.h:57:11: warning: 'uint16_t BodySW::locked_axis' [-Wreorder]
servers/physics/body_sw.cpp:756:1: warning: when initialized here [-Wreorder]
```
Nothing really relevant for us, but it's not a bad consistency
improvement anyway so worth taking.
