Huge changes to `FlxPreloader` and added `FlxPreloaderBase`
`FlxPreloader` is now just the 'skin' for `FlxPreloaderBase`, which users can make their own version of for their own Preloaders.
`FlxPreloaderBase` has been changed to no longer extend `NMEPreloader` (unless the 'js' flag is true, in which case it bypasses all the preloader logic anyway and ONLY uses `NMEPreloader`)
`FlxPreloaderBase` should now work for all situations an no longer 'get stuck' - and allow for `minDisplayTime` to be set to '0'.
Cleaning up and formatting tweaks for `FlxPreloader`
More attempts to fix `FlxPreloader`
Added comments to `FlxPreloaderBase`.
Merge branch 'dev' of https://github.com/HaxeFlixel/flixel into dev

Conflicts:
	flixel/system/FlxPreloader.hx
Removed traces from `FlxPreloaderBase`
Merge pull request #1020 from SeiferTim/New-Preloader-Logic

New preloader logic