refactor BigWig/RequestWorker preparing to work on #312
rewrite BigWig/RequestWorker to be non-recursive, references #312
improve bigwig performance
further improve BigWig performance, references #312
update release notes, closes #312
add MYMETA.* to gitignore
bugfix to new bigwig code
pass config data to glyphs
fix compact display mode layout bug
Merge branch 'master' into nextgenconfig

Conflicts:
	.gitignore
	src/JBrowse/View/Track/CanvasFeatures.js