Initial commit

This is the initial commit. It includes the source files
Fl_MIDIKeyboard.h, Fl_MIDIKeyboard.cpp, MIDIDriverWin32.h,
MIDIDriverWin32.cpp, the test file test_Fl_MIDIKeyboard.cpp, plus the
doxyfile and the HTML documentation generated by Doxygen
Merge remote-tracking branch 'origin/master'