iOS: change platform code to support plugins

platform/iphone/os_iphone.h

@@ -44,6 +44,9 @@
 #include "servers/visual/rasterizer.h"
 #include "servers/visual_server.h"
 
+extern void godot_ios_plugins_initialize();
+extern void godot_ios_plugins_deinitialize();
+
 class OSIPhone : public OS_Unix {
 
 private:

platform/iphone/os_iphone.mm

@@ -195,6 +195,7 @@ MainLoop *OSIPhone::get_main_loop() const {
 };
 
 void OSIPhone::set_main_loop(MainLoop *p_main_loop) {
+	godot_ios_plugins_initialize();
 
 	main_loop = p_main_loop;
 
@@ -319,6 +320,8 @@ void OSIPhone::finalize() {
 		memdelete(ios);
 	}
 
+	godot_ios_plugins_deinitialize();
+
 	visual_server->finish();
 	memdelete(visual_server);
 	//	memdelete(rasterizer);