This PR places all LMMS symbols into namespaces to eliminate any potential future name collisions between LMMS and third-party modules.
Also, this PR changes back `LmmsCore` to `Engine`, reverting c519921306 .
Co-authored-by: allejok96 <allejok96@gmail.com>
- Double-click mmpz file in finder will now open properly on macOS
- Adds new MainApplication class for listening to QEvent::FileOpenEvent
- Queues open events until the application is ready to recieve them
- Closes#665