Renamed OpenFileDialog to ImportFilesDialog.
Renamed SaveMuxedFileDialog to MuxAsDialog.
Renamed SaveRawFilesDialog to ExtractToDialog.
Renamed MP4BoxBinaryDialog to FindMP4BoxDialog.
Tweaking the ExtractToDialog.

Still don't think this "extract to dir" is a good user experience,
but I'm not really sure how else to solve it.
Updated todo.
Tweaking the MuxDialog.
Don't put everything in the constructor.
Comments.
Removed the menu bar.
Updated todo.
This is what I want the readme to look one day.