fix for issue #682
some changes regarding renaming FlxSprite's clone() to loadFromSprite()
less calculations for FlxMath.roundDecimal()
replaced math.pow with just multiplication in flxmath.rounddecimal
Corrected issues with multi-touch support in buttons.
Removing bad inline candidates.
Removed unnecessary code.

Since I commented out the add listener, it makes sense to remove the
remove listener call too.
Add the option to, when recycling an object from a FlxTypedGroup, force the object to be the specified class and not a super class of that.
Merge pull request #684 from newtzgames/dev

Corrected issues with multi-touch support in buttons.
Fix typo in description of TO_DEG
little change for pixels setter in FlxSprite (just to be sure)
introduction of collision types enum for less usage of Std.is()
introducing FlxSpriteGroup2 (new experimental version of FlxSpriteGroup)
little code rearranging in sprite groups
very small change for sprite group 2
function names correction
added method's agrs for callAll()
Damn, i forgot to add Args param
removed IFlxPoint interface
less reading of collision types from objects