Added function mergeFlxSprite

Quickly draw one FlxSprite on top of another.
Fixed mergeFlxSprite

Maybe I should commit the right version or something oops...
Adding FlxAndroidKeys.hx

Adding new input to handle built-in Android keys/buttons.
Removing debugging stuff...
Create FlxAndroidKeyList.hx
Added FlxAndroidKeys

Added reference to FlxAndroidKeys.
Update FlxAndroidKeys.hx - fixed bug with Menu key

Okay, so the value for the Menu Key was too big to work in an array the same way as in FlxKeyboard... so I changed things around to use a Map instead of an array.

If anyone can figure out any other Android key constants, please add them!
Add iterator for groups (all, dead, alive, exists)
iteratorAlive: check if alive AND exists
Rename FlxGroupIterator to FlxTypedGroupIterator
Fix typo in comment `members` to `member`
Inlined `iterator()`
Change `iteratorAlive`, `iteratorDead` and `iteratorExists` to properties to get rid of `()`
Add `forEach`, `forEachAlive`, `forEachDead` and `forEachExists`
Delete old FlxGroupIterator.hx file. Missing in last commit
Fix bug: You couldn't iterate over an element that had called remove without slice
Replace `T` with `FlxBasic`
Merge branch 'dev' of https://github.com/HaxeFlixel/flixel into HaxeFlixel-dev

Conflicts:
	flixel/util/FlxSpriteUtil.hx
@crazysam suggestion
Fix parameter signature of forEachDead and forEachExists
Added StartFullscreen parameter to FlxGame (desktop)

Added a new parameter to FlxGame's constructor that allows you to pass
if you want to start the game in Fullscreen or not.
This is useful if you want to say, load the Fullscreen status from a
FlxSave and then decide to start Fullscreen or not based on the user's
options, instead of starting with whatever the Project.xml says, and
then switching later - makes it a little nicer and smoother.
Updated FlxG to use FlxG.gamepads on HTML5 target
Updated FlxGamepad to handle input on HTML5 target
Updated FlxGamepadManager to work on HTML5 target