MultiplayerPeer changes:
- Adds is_server_relay_supported virtual method
Informs the upper MultiplayerAPI layer if it can signal peers connected
to the server to other clients, and perform packet relaying among them.
- Adds get_packet_channel and get_packet_mode virtual methods
Allows the MultiplayerAPI to retrieve the channel and transfer modes to
use when relaying the last received packet.
SceneMultiplayerPeer changes:
- Implement peer signaling and packet relaying when the MultiplayerPeer
advertise they are supported.
ENet, WebRTC, WebSocket changes:
- Removed custom code for relaying from WebSocket and ENet, and let it
be handled by the upper layer.
- Update WebRTC to split create_client, create_server, and create_mesh,
with the latter behaving like the old initialize with
"server_compatibility = false", and the first two supporting the upper
layer relaying protocol.
- RPC configurations are now dictionaries.
- Script.get_rpc_methods renamed to Script.get_rpc_config.
- Node.rpc[_id] and Callable.rpc now return an Error.
- Refactor MultiplayerAPI to allow extension.
- New MultiplayerAPI.rpc method with Array argument (for scripts).
- Move the default MultiplayerAPI implementation to a module.
* Map is unnecessary and inefficient in almost every case.
* Replaced by the new HashMap.
* Renamed Map to RBMap and Set to RBSet for cases that still make sense
(order matters) but use is discouraged.
There were very few cases where replacing by HashMap was undesired because
keeping the key order was intended.
I tried to keep those (as RBMap) as much as possible, but might have missed
some. Review appreciated!
Move multiplayer classes to "core/multiplayer" subdir.
Move the RPCConfig and enums (TransferMode, RPCMode) to a separate
file (multiplayer.h), and bind them to the global namespace.
Move the RPC handling code to its own class (RPCManager).
Renames "get_rpc_sender_id" to "get_remote_sender_id".
