[sdiy] avrsyn update

[Daniel Kruszyna]

I've done some more work on my avrsyn code and updated my site
at http://krue.net/avrsyn/

There are now two adsr envelopes: one for the dca and one for the
filter. Because of the lack of panel controls, the envelopes are
controlled with MIDI CC messages.

I also modified the lfo and envelope routines to run at a constant
interval and created an expanded table to take the place of the
TIMETORATE conversion.

-- Daniel