Pull request from N. Cassetta

This is the final result of my work!
I've merged the edit functions into my master branch, so now MIDITrack and MIDIMultiTrack have these.
Moreover, I did some work on the MIDIDriver class: I tried to move as many methods a possible from MIDIDriverWin32 to MIDIDriver (making them pure virtual) and to eliminate WIN32 specific code from other files not in Win32 dir.
So, now all should compile even under other OS: the AdvancedSequencer should only set a dummy MIDIDriverDump as driver.
Some answers:
1) In the files advancedsequencer.h and manager.h I added two little functions specific for Linux: is it correct #ifdef __linux? (and shouldn't #ifdef WIN32 be #ifdef _WIN32?).
2) I added three new example files in dir \examples\win32 but I don't know make and similar, so I didn't upgrade the \build dir
3) I tested all only under Windows, and it is stable, but I didn't tested under other OS.
I think it, after some testing, could be moved into the master: