Second pull request by NCassetta

I would submit to you this second pull request: main changes include
1) Rearranged classes MIDISequencer, AdvancedSequencer, MIDIManager, MIDIDriverWin32, inlining many simple function
2) Added a lot of documentation (doxygen comments in the headers) and a new NCDoxyfile (I could not run yours)
3) Added some functions to the classes and the capability for MIDIDriverWin32 to send Sysex messages

Before merging, I would ask you:
1) Should I include html docs generated by doxygen? They are more than 600 files ...
2) Would you take a look to sysex sending (in MIDIDriverWin32.cpp?) It would be simpler with a slighty modify to class MIDISystemExclusive, but I think there might be problems of compatibility ...
3) Would it be better to branch for adding new features? I am new to Github and collaborative coding, so I am not handy about these things 
N. Cassetta