Optmized data sent during RPC and RSet calls.

- Now is sent the method ID rather the full function name.
- The passed IDs (Node and Method) are compressed so to use less possible space.
- The variant (INT and BOOL) is now encoded and compressed so to use much less data.
- Optimized RPCMode retrieval for GDScript functions.
- Added checksum to assert the methods are the same across peers.

This work has been kindly sponsored by IMVU.

core/script_language.cpp

@@ -32,6 +32,7 @@
 
 #include "core/core_string_names.h"
 #include "core/project_settings.h"
+#include <stdint.h>
 
 ScriptLanguage *ScriptServer::_languages[MAX_LANGUAGES];
 int ScriptServer::_language_count = 0;
@@ -644,6 +645,14 @@ Variant PlaceHolderScriptInstance::property_get_fallback(const StringName &p_nam
 	return Variant();
 }
 
+uint16_t PlaceHolderScriptInstance::get_rpc_method_id(const StringName &p_method) const {
+	return UINT16_MAX;
+}
+
+uint16_t PlaceHolderScriptInstance::get_rset_property_id(const StringName &p_method) const {
+	return UINT16_MAX;
+}
+
 PlaceHolderScriptInstance::PlaceHolderScriptInstance(ScriptLanguage *p_language, Ref<Script> p_script, Object *p_owner) :
 		owner(p_owner),
 		language(p_language),