various audio improvements (see details)

- updated to the last howler v1.1.19 version
- re-fixed audio not working with the CocoonJS accelerated webGL view
(in Howler.js), see
https://github.com/goldfire/howler.js/commit/a9ea27abc0ec2f03e5df4be84c012bdee20484e8
- documentation fix for me.audio.resumeTrack()