Update wavesurfer.js
Merge pull request #257 from sorensenjs/patch-1

Sets correct value in skipBackwards
fix typos
use local screenshot
Merge pull request #258 from thijstriemstra/master

fix typos
bump version for #262
Merge branch 'master' of github.com:katspaugh/wavesurfer.js
update build
typo in docs; resolves #260
add region labels