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The display is no longer updated if any unwatched robots are in the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 .