Setup espeak TTS. Fix "velocity" -> "gain".

I was originally thinking the velocity sensor would adjust the midi note velocity.
The downside to this is that you have to wait for a note to play to "feel" the volume change.

When changed to alter the gain of the synth itself, it is much smoother -- works for any
sound, even those that have already started playing.

FossilOrigin-Name: 9b5a893d5b6e3aed1e11d0b984b5f498d9b67f55cda304bbef4179944ca6260f

theremin/lib/fluidsynth.rb

@@ -54,7 +54,7 @@ class FluidSynth
 		@host = host
 		@port = port
 		@lastnote = nil
-		@velocity = 0
+		@velocity = 80
 	end
 
 	# The TCP socket to fluidsynth.