Fixes for new two-dash long command line arguments

- Fixes some single-dash leftovers that were missed in the previous commit
- Reorder the help output for clarity, and document missing options
- Drop obsolete options: --noop, --pack, --editor-scene, --level, --import, --import-script, --no-quit
- Improve error message on malformed arguments and do not display help on error
- Always use long form of arguments when starting a new Godot process from C++, for clarity and easy grepping
- Cleanup obsolete code here and there

platform/uwp/app.cpp

@@ -512,7 +512,7 @@ void App::UpdateWindowSize(Size size) {
 
 char **App::get_command_line(unsigned int *out_argc) {
 
-	static char *fail_cl[] = { "-path", "game", NULL };
+	static char *fail_cl[] = { "--path", "game", NULL };
 	*out_argc = 2;
 
 	FILE *f = _wfopen(L"__cl__.cl", L"rb");