Merge pull request #74 from wingedfox/master

New features (proxyXHR.append, X-Last-Known-Byte, pause event)
fixed flash.abort
Merge branch 'master' of https://github.com/mailru/FileAPI

Conflicts:
	FileAPI.flash.swf
Merge pull request #77 from im-saxo/master

* fix flash.abort
* v1.2.3: fixed flash.abort, #75
Merge branch 'master' into dev
Merge pull request #76 from wingedfox/master

Fixes and features
fixed range for empty slice