* added MidiLibraryManager together with tests.
* added error log when failing to add midi + minor formatting.
* additional error logging for midi library.
* fixed TestRemoveMidiFile failing due to new error logging.
* improved error logging.
* switched from string file names to ResPath
* renamed to MidiFileCollection and moved to Content.Client.Audio.Midi
* updated xml docs
* readded the Manager suffix that I totally didn't forget + some formatting.
