Initial checkin of AutoHotkey-Midi library

* includes support for MIDI input events
* includes support for most all documented MIDI events, including sysex
* builds an event object that holds appropriate data for the midi event, tailored to the event (ie: NoteOn/NoteOff have a note value, etc)
* automatically initializes and cleans up libraries on object creation and destruction
* calls labels based on the MIDI input event, so that you can code scripts similar to how the usual autohotkey keypress input scripts work
* see readme for TODO items
Initial readme file for AutoHotkey-Midi