js/things: prototype thing and thing manager.

simple beasts that eat 'stuff' if they land on it.
movement is random, no guidance yet.
if energy level falls to 0, dead.
TODO:
 - instead fo storing in a grid, store in an object.
 - `findNearest` funciton requried for info panel
 - genes
 - simple movemenet rules
js/tsg: `click` function. render things on second pass. incubate/instantiate things
js/stuff: scale up life span by 10. better spawn rules.
index.html: include things, show click position