Merge pull request #1 from HaxeFlixel/master

Updating Master
Adding FlxAsyncLoop

This class is very basic right now, but could be expanded for more
usages (Arrays?) used to easily run loops that can be done
asynchronously so you can track progress with bars/%/whatever...
Added Documentation to FlxAsyncLoop
Changes to FlxAsyncLoop

Minor changes to make it work better.
Switched from `async` package to `util`
Oops...
Callback fixed...
Constructor was wrong...
Fixed ALL the Things!

...I hope...
Update FlxAsyncLoop.hx

Minor tweaks - removed superfluous temp variable for loop
Removed '?' from IterationsPerUpdate parameter.
Merge pull request #32 from SeiferTim/master

Added FlxAsyncLoop
Merge branch 'master' into dev