Viewing: Aria Maestosa 1.0b7

Aria Maestosa 1.0b7 release includes, among other changes, better support of the midi specs and a huge speed-up when loading files.
Changes details :
- Added support for channels
- Reduced memory usage
- Opening files is now much faster
- More major code cleanup
- Fixed top bar getting messed up when dealing with multiple songs in particular circumstances
- Improved display of disabled song names to be easier on the eyes
- Fixed localisation errors on computers whose localisation is not supported