Robot's now run once or repeatedly

Added a new check box to the backside.
Added JSON support for new robot properties

run_once and next_robot are now part of the generated JSON.
Fixed a bug in backside_widget calculation

Widgets were added due to both frontside and backside.
Toggling run/stop only top-level backside

Clicking on a descendant of a top-level backside no longer toggles
run/stop.
Fixed a robot JSON bug

'run_once' now works with drag and drop cross windows.
Fix to run/pause button label

Triggered a JQuery error if button not visible.