New P600fw alpha (june 14)

I forgot to post about this one, made it almost a month ago.

Notable changes from stable 2.0:

- Enabled external filter CV input.
- Added "voice spread" feature, toggled with "from tape" + 9, it does two things:
     - Enables unison detune in poly mode.
     - Adds subtle per-voice envelope timings changes, to mimic tolerances of analog components.

Download links at: http://sfx.gligli.free.fr/zik/p600/dev/2014-06-14/