-Made it possible to change the editor theme
-Added two options to theme editor plugin to create empty template themes and editor themes
-Make sure that saved themes to .tres keep the null theme fields, to make it easier to keep those when saving/loading the theme
-ItemList control for easier lists/thumbnails
-New file dialog, with support for thumbnails, favorites, recent places,
etc
-Moved .fscache out of the project, no more bugs due to committed/pulled
.fscache!
-Dir dialog now sorts directories
-made GUI Theme editor usable
-editor does not allow to export or create .pck in the same path as a project
-changed .pck format (lacked support for versioning so couldn't change it), previous was causing crashes and is now incompatible, just re-export.
-will not look for .pck files recursively, was causing unexpected behaviors
-fixed execution of Godot in paths with non unicode characters in Windows, OSX and Linux.
