removes flac test as it was broken on osx, adds get_audio_devices
adds Gain node with * operator
adds julia 0.2+ to REQUIRE
Merge branch 'master' into dev_select
refactored AudioNode to contain a AudioRenderer, tests passing
adds some design notes
fixes issue where portaudio task was killing the root mixer
fixes imprecise SinOsc
ports AudioInput to new type structure
adds WhiteNoise AudioNode
adds LinRamp node
adds ability to control SinOsc freq from a signal
adds test to SinOsc render to test for allocation
SinOsc{Float32} allocation is way down
eeked some more allocation out of SinOsc
got LinRamp allocation down to 240bytes
dropped allocation on SinOsc{AudioNode}
render alloc on ArrayPlayer down to 192bytes. can probably do better
tweaks TestNode so it doesn't allocate substantially
drops allocation of MixRenderer to 64bytes