Contents of thought bubbles displayed
Adjust 'top' when robot first displayed

Since resource doesn't display thought bubble.
Erased numbers displayed correctly
Erased boxes display correctly
Added erase/un-erase button

When appropriate.
Fixed copying bugs

Robot actions (body) wasn't being copied.
Numbers with robots were being deep copied including the robots, etc.
Various cosmetic improvements.
All test robots working again.
Numbers with too little width use small font

So at least something is displayed.
Added untrained robots to resources
Better error handing in drop_on

Handles case where thing_in_hand doesn't respond to 'drop_on'.
Improved number display

Better handling of too narrow space
Clicks on resources ignored

Previously broke entire app.
Prevents infinite loop in click handler

If frontside isn't 'normal'.