Made JSON drop more robust

Works to drag JSON text from a browser.
Updated constructionism paper
Data transfer now supports both text and text/html

text/html makes sense (and opens up for future enhancements when
dragging other HTML elements in) but causes an IE9 error so both used
now.
Numerator and denominator fields are text areas

Since values can be too large for a text input (single line)
Display is updated at the end a cycle

The display is no longer updated if any unwatched robots are in the
middle of running their actions .
Fixed a bug training robots to remove

If removed from a container couldn't compute the path.
Fixed number display problem

Sometimes the number has no height and was being displayed with a small
font. Better to wait until the DOM knows its height.
Watched robots not broken by moving context

Moving elements while a robot is working can cause the elements to
temporarily have no position which caused robot animation to trigger an
exception. This works around it by sending the robot off to the upper
left corner.
Fixed the generated description of box paths

It was saying 'number what is in ...' now is 'number that is in ...'
Fixed the ordinals greater than 3

Says '4th' instead of '3th', etc.
Boxes created from json or by copying are parents

Hole contents weren't informed of the box they were in.
Watched robots editing use correct backside

Was using the robot's backside rather than the widget being edited.
Dragged the wrong element

In some circumstances an ancestor was being dragged rather than the
proper element.

This also caused the placement of a robot to another spot a backside to
move the backside so the robot's relative position didn't change.
Watched robots semi-transparent

So can see what they are hovering over, etc.
Better handling of where watched robots go

When they don't know where a target element is or it isn't visible.
Better display of numbers

If the area wasn't wide enough and the number had an operator you only
saw the operator.
Boxes no longer change size

Due to the presence of an empty-hole element along with the hole
contents.

Also the size of elements after being taken out of a hole was not
consistently being restored.
Better dragging

Since it uses srcElement if it can.
Updated test Fibonacci

That also maintains the ratio of successive values.
Update index.html and added save.html

As a quick-and-dirty way to save one's work.