Updated introductory talk slides

To leave room for green flag and stop sign.

And to use iframe for demo.
Major change in representing visibility

Front and back sides now 'know' if they are visible. No reliance upon
the DOM anymore. Is much faster and reliable (e.g. a robot may put a
bird in a hole and give it something and the call to render hasn't yet
updated the DOM to put the bird in the hole).
Fixed recently visibility bugs
Updated test programs
Robot condition widgets updated when changed

They now have their visible flag set and hence when altered (e.g.
erased) the display updates.
Can create nests from JSON without GUID

E.g. resource nests.
Better position for copies made by robots

The copies now are near the original.
Multiple clicks on green flag ignored

If already running clicks do nothing.
Improvements to infinity activity
Fixed problem stopping robots
Fixed a robot dropping on backside problem

Was ending up near 0,0
Complete updated version of cardinality excercise
Further improvements to the cardinality excercise
Widgets no longer resizable inside boxes

Fixed #182.
Fixed a typo
Updated compiled version
Merge pull request #187 from ToonTalk/master

Updating gh-pages to master