[Net] Modularize multiplayer, expose MultiplayerAPI to extensions.

- 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.

visual_script.cpp

@@ -948,7 +948,7 @@ bool VisualScript::are_subnodes_edited() const {
 }
 #endif
 
-const Vector<Multiplayer::RPCConfig> VisualScript::get_rpc_methods() const {
+const Variant VisualScript::get_rpc_config() const {
 	return rpc_functions;
 }
 
@@ -1012,22 +1012,16 @@ void VisualScript::_set_data(const Dictionary &p_data) {
 	for (const KeyValue<StringName, Function> &E : functions) {
 		if (E.value.func_id >= 0 && nodes.has(E.value.func_id)) {
 			Ref<VisualScriptFunction> vsf = nodes[E.value.func_id].node;
-			if (vsf.is_valid()) {
-				if (vsf->get_rpc_mode() != Multiplayer::RPC_MODE_DISABLED) {
-					Multiplayer::RPCConfig nd;
-					nd.name = E.key;
-					nd.rpc_mode = vsf->get_rpc_mode();
-					nd.transfer_mode = Multiplayer::TRANSFER_MODE_RELIABLE; // TODO
-					if (rpc_functions.find(nd) == -1) {
-						rpc_functions.push_back(nd);
-					}
-				}
+			if (!vsf.is_valid() || vsf->get_rpc_mode() == MultiplayerAPI::RPC_MODE_DISABLED) {
+				continue;
 			}
+			Dictionary nd;
+			nd["rpc_mode"] = vsf->get_rpc_mode();
+			nd["transfer_mode"] = MultiplayerPeer::TRANSFER_MODE_RELIABLE; // TODO
+			nd["call_local"] = false; // TODO
+			rpc_functions[E.key] = nd;
 		}
 	}
-
-	// Sort so we are 100% that they are always the same.
-	rpc_functions.sort_custom<Multiplayer::SortRPCConfig>();
 }
 
 Dictionary VisualScript::_get_data() const {
@@ -1811,8 +1805,8 @@ Ref<Script> VisualScriptInstance::get_script() const {
 	return script;
 }
 
-const Vector<Multiplayer::RPCConfig> VisualScriptInstance::get_rpc_methods() const {
-	return script->get_rpc_methods();
+const Variant VisualScriptInstance::get_rpc_config() const {
+	return script->get_rpc_config();
 }
 
 void VisualScriptInstance::create(const Ref<VisualScript> &p_script, Object *p_owner) {

visual_script.h

@@ -235,7 +235,7 @@ private:
 	HashMap<StringName, Function> functions;
 	HashMap<StringName, Variable> variables;
 	HashMap<StringName, Vector<Argument>> custom_signals;
-	Vector<Multiplayer::RPCConfig> rpc_functions;
+	Dictionary rpc_functions;
 
 	HashMap<Object *, VisualScriptInstance *> instances;
 
@@ -363,7 +363,7 @@ public:
 
 	virtual int get_member_line(const StringName &p_member) const override;
 
-	virtual const Vector<Multiplayer::RPCConfig> get_rpc_methods() const override;
+	virtual const Variant get_rpc_config() const override;
 
 #ifdef TOOLS_ENABLED
 	virtual bool are_subnodes_edited() const;
@@ -444,7 +444,7 @@ public:
 
 	virtual ScriptLanguage *get_language();
 
-	virtual const Vector<Multiplayer::RPCConfig> get_rpc_methods() const;
+	virtual const Variant get_rpc_config() const;
 
 	VisualScriptInstance();
 	~VisualScriptInstance();

visual_script_nodes.cpp

@@ -90,7 +90,7 @@ bool VisualScriptFunction::_set(const StringName &p_name, const Variant &p_value
 	}
 
 	if (p_name == "rpc/mode") {
-		rpc_mode = Multiplayer::RPCMode(int(p_value));
+		rpc_mode = MultiplayerAPI::RPCMode(int(p_value));
 		return true;
 	}
 
@@ -261,11 +261,11 @@ int VisualScriptFunction::get_argument_count() const {
 	return arguments.size();
 }
 
-void VisualScriptFunction::set_rpc_mode(Multiplayer::RPCMode p_mode) {
+void VisualScriptFunction::set_rpc_mode(MultiplayerAPI::RPCMode p_mode) {
 	rpc_mode = p_mode;
 }
 
-Multiplayer::RPCMode VisualScriptFunction::get_rpc_mode() const {
+MultiplayerAPI::RPCMode VisualScriptFunction::get_rpc_mode() const {
 	return rpc_mode;
 }
 
@@ -311,14 +311,14 @@ void VisualScriptFunction::reset_state() {
 	stack_size = 256;
 	stack_less = false;
 	sequenced = true;
-	rpc_mode = Multiplayer::RPC_MODE_DISABLED;
+	rpc_mode = MultiplayerAPI::RPC_MODE_DISABLED;
 }
 
 VisualScriptFunction::VisualScriptFunction() {
 	stack_size = 256;
 	stack_less = false;
 	sequenced = true;
-	rpc_mode = Multiplayer::RPC_MODE_DISABLED;
+	rpc_mode = MultiplayerAPI::RPC_MODE_DISABLED;
 }
 
 void VisualScriptFunction::set_stack_less(bool p_enable) {

visual_script_nodes.h

@@ -33,6 +33,7 @@
 
 #include "core/object/gdvirtual.gen.inc"
 #include "core/object/script_language.h"
+#include "scene/main/multiplayer_api.h"
 #include "visual_script.h"
 
 class VisualScriptFunction : public VisualScriptNode {
@@ -49,7 +50,7 @@ class VisualScriptFunction : public VisualScriptNode {
 
 	bool stack_less;
 	int stack_size;
-	Multiplayer::RPCMode rpc_mode;
+	MultiplayerAPI::RPCMode rpc_mode;
 	bool sequenced;
 
 protected:
@@ -90,8 +91,8 @@ public:
 	void set_stack_size(int p_size);
 	int get_stack_size() const;
 
-	void set_rpc_mode(Multiplayer::RPCMode p_mode);
-	Multiplayer::RPCMode get_rpc_mode() const;
+	void set_rpc_mode(MultiplayerAPI::RPCMode p_mode);
+	MultiplayerAPI::RPCMode get_rpc_mode() const;
 
 	virtual VisualScriptNodeInstance *instantiate(VisualScriptInstance *p_instance) override;