UI Adjustments/additions

I decided it might be fun to change the character select so the backs of the characters heads were displayed, then when you select the character the sprite changes to a facial view.  :)

Realised that the game could not be paused when using a touch screen, so created an on-screen button to allow that.

Someone suggested that it might be good to be able to play using a mouse pointer & on-screen controls...so now there is a tick box on the title screen, if you tick that the on-screen controls will be forced on (i.e. will not disappear after a few seconds of inactivity) so you can click on them to move, throw food, etc.