Update Howler to latest 1.1.25 version

see the Howler changelog for further details :
https://github.com/goldfire/howler.js/blob/master/CHANGELOG.md
[documentation] removed the class.Error documentation

this was kind of "polluting" the class list, and i would rather document
this through the Error class (by specifying that all end-user classes
are derivating from this one, and giving some example)
[documentation] improved documentation for the new `me.collision` API
[#545] removed the old jsdoc template
[#546] fixed collision layer rendering issue with isometric map
avoid referring to `_default` when calling `sound.play()`

this is an internal value/reference only, that changed anyway in the 2.0
branch. @see discussion here :
https://github.com/goldfire/howler.js/issues/193
[documentation] fixed the `me.body.onCollision` parameter type and description
[#543] removed the old useless object types under `me.game` (replaced by me.collision.types)
fix a link in the README file
testing video scaling, fixed initial draw width & height destination
corrected backbuffer canvas sizing.
Merge branch 'master' into ticket-144