when switching browser tabs, recording behavior isn't entirely correct (rare)

[binarykitchen]

to reproduce

1. use the simple example
2. start recording and switch away to another tab asap
3. after a while come back and look in the console, it recorded twice and video lengths were wrong

[binarykitchen]

also test carefully the pausing feature when using audio

[binarykitchen]

almost there, one last issue regarding fixed delta remains, see https://github.com/hapticdata/animitter/issues/5#issuecomment-292693344