[Fluxus] fluxa fixes

[David Griffiths]

Hi all,

I've pushed some more changes to fluxa, work on the temporal recursion,
but also a big fix for the internals of the sound engine.

It turns out (as we suspected) that there was a bottleneck in the synth
command ringbuffer for the realtime thread - it was trying to allocate
4k per message out of 2.6Mb of ringbuffer, so max 64 messages at any one
time.

I suspect this was due to the fact I originally designed this code for
larger messages with lots of parameters, fluxa sends lots of little
messages to construct it's graphs.

Anyway, it's now possible to have much more complex synth graphs playing
faster music!

cheerio,

dave