Misc Fixes

==========

-NOTIFICATION_WM_QUIT fixed on android (seems tha way this is reported changed in newer sdk)
-WIP implementation of APK Expansion APIs for publishing games larger than 50mb in Play Store
-Feaures in the new tutorials are all present in the sourcecode
-This (hopefully) should get rid of the animation list order getting corrupted
-Improved 3D Scene Importer (Skeletons, Animations and other stuff were not being merged). Anything missing?
-In code editor, the automatic syntax checker will only use file_exists() to check preload() else it might freeze the editor too much while typing if the preload is a big resource
-Fixed bugs in PolygonPathFinder, stil pending to do a node and a demo

scene/3d/room_instance.cpp

@@ -99,7 +99,7 @@ RES Room::_get_gizmo_geometry() const {
 	mat->set_line_width(4);
 	mat->set_flag(Material::FLAG_DOUBLE_SIDED,true);
 	mat->set_flag(Material::FLAG_UNSHADED,true);
-	mat->set_hint(Material::HINT_NO_DEPTH_DRAW,true);
+//	mat->set_hint(Material::HINT_NO_DEPTH_DRAW,true);
 
 	surface_tool->begin(Mesh::PRIMITIVE_LINES);
 	surface_tool->set_material(mat);