~Partial Blitting~

Partial blitting is when you blit to an internal bmd and display that on
a bitmap.  One bitmap per Dude.  This lets you use the lovely
DisplayObject properties of bitmap, like scaleX and rotation.  I changed
the Dude class to implement this.  It doesn't get the same "thousands of
objects" performance as straight blitting, but it's still faster than
sprites and such.  If you require clicking, you have to wrap the bitmap
in a DisplayObjectContainer, usually a Sprite.

Left and right now flip the player's sprite.