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/export/export.cpp

@@ -1330,7 +1330,7 @@ public:
 		}
 
 		if (!(p_flags & DEBUG_FLAG_DUMB_CLIENT)) {
-			cl.push_back("-path");
+			cl.push_back("--path");
 			cl.push_back("game");
 		}