Add volume control

[santolucito]

add a master volume field to the global beat dict here:

SequencerLiveCoding/public/js/beat.js

Line 23 in ea724cd

var beatReset = {"kitIndex":0,"effectIndex":0,"tempo":100,"swingFactor":0,"effectMix":0.25,"kickPitchVal":0.5,"snarePitchVal":0.5,"hihatPitchVal":0.5,"tom1PitchVal":0.5,"tom2PitchVal":0.5,"tom3PitchVal":0.5,"rhythm1":[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],"rhythm2":[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],"rhythm3":[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],"rhythm4":[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],"rhythm5":[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],"rhythm6":[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]};

then use that field in play.js here:

SequencerLiveCoding/public/js/play.js

Line 40 in ea724cd

function playNote(buffer, pan, x, y, z, sendGain, mainGain, playbackRate, noteTime) { //add durationVal