Fix Input Handling

related to: http://forum.haxepunk.com/index.php?topic=675.0

Haxepunk crashes with access violation on cpp/Windows when pressing Numlock, Menu and other keys.
The keys that cause the crash have a high key code (+1 billion) unlike the others (<200).
When the Numlock key is pressed Input.hx tries to acess an array with this key code wich causes the array size to increase by 1 billion. My guess it that Windows can't allocate that much memory and exits the program.

Fixed by using a Map instead of an Array.
Maybe there's a better solution because map accesss it slower than array access and there and i think there are only like 2-4 keys with such a high key code.