Multiway now keeps tracking of keydown's

Issue: Currently, keydown will only hold keys activated through actual keyboard input. 

This small change allows the user to keep track of keydowns when **KeyDown** event is triggerred directly using ```Crafty.trigger("KeyDown", key)```. It thus allows one to also use Keyboard's component ```isDown``` function. I did this modification in the making of a simple GUI with directional arrow keys for use with mobiles.