MIDI fixes for Teensy and Windows 3.1 instrument defs

[DhrBaksteen]

• This fixes issue #34 in TeensyMidi where MIDI events sent to a channel > 16 would cause unintended behavior such as random instrument changes and volumes.
• This fixes an issue in TeensyMidi where a volume control change change would cause channels to either go to minimum or maximum volume. Volme is now limited to 80% to prevent instruments from clipping.
• Included the MIDI instrument definitions used in Windows 3.1 by to SoundBlaster driver. These work best with MIDIs created for windows.