-fixed bug in Button now exporting font property

-made GUI Theme editor usable
-editor does not allow to export or create .pck in the same path as a project
-changed .pck format (lacked support for versioning so couldn't change it), previous was causing crashes and is now incompatible, just re-export.
-will not look for .pck files recursively, was causing unexpected behaviors
-fixed execution of Godot in paths with non unicode characters in Windows, OSX and Linux.

tools/editor/project_export.cpp

@@ -374,6 +374,24 @@ void ProjectExportDialog::_export_mode_changed(int p_idx) {
 
 void ProjectExportDialog::_export_action(const String& p_file) {
 
+	String location = Globals::get_singleton()->globalize_path(p_file).get_base_dir().replace("\\","/");
+
+	while(true) {
+
+		print_line("TESTING: "+location.plus_file("engine.cfg"));
+		if (FileAccess::exists(location.plus_file("engine.cfg"))) {
+
+			error->set_text("Please export outside the project folder!");
+			error->popup_centered(Size2(300,70));;
+			return;
+		}
+		String nl = (location+"/..").simplify_path();
+		if (nl.find("/")==location.find_last("/"))
+			break;
+		location=nl;
+	}
+
+
 	TreeItem *selected = platforms->get_selected();
 	if (!selected)
 		return;