-Support for changing fonts

-Detect when free() might crash the project and throw error
-fixed 2D Bounce in physics (3d still broken)
-renamed “on_top” property to “behind_parent”, which makes more sense, old on_top remains there for compatibility but is invisible.
-large amount of fixes

core/io/resource_format_binary.cpp

@@ -949,6 +949,7 @@ String ResourceInteractiveLoaderBinary::recognize(FileAccess *p_f) {
 
 	} else if (header[0]!='R' || header[1]!='S' || header[2]!='R' || header[3]!='C') {
 		//not normal
+		error=ERR_FILE_UNRECOGNIZED;
 		return "";
 	}