Restore the drawsBounds shape drawing

[nwinter]

We currently have bounds drawing disabled, which makes Gridmancer and Criss-Cross not work well:

      # TODO: add back bounds
#      @addMark('bounds').toggle true if @thang?.drawsBounds

We need to refactor the buildBounds method like buildShadow was refactored to use a custom graphic in the layer instead of just trying to draw a sprite directly.

[nwinter]

We re-implemented Gridmancer without these, although they'd still be nice. If we aren't going to do this again, we should strip out the code for it.