cut with immutables and new webgl-waveform

webgl-waveforms is missing some render code still
webgl-waveform now partly works

Shaders and buffer code seem to be functioning ok, but the other bits
don't yet work.
webgl-waveform nearly fully operational

still need code for copying valid old images
changed T.$tile_ to T.tiles and fixed some bugs
added temporalcorr.js & improved display toggling

temporalcorr doesn't plot yet but hopefully does all the preparatory
work needed
temporalautocorr now plots
temporalcorr.js now uses a worker
created worker-bridge.js & now used in tempolcorr

worker-bridge also has its own gist on github
bug fixes in temporalcorr.js
ratemap with bridged-worker plus T.TC bugfixes
webgl-waveforms copies old chans plus T.RM bugfix
improved merge css and snapping
bug fixes for tiles