scriptingAPI loadModel: pass onLoadScript not function

The optional second argument to loadModel must now be
the string form of the onLoadScript -- not the actual
function object.

Example:

"action": "loadModel('npPulling', 'start();');"

However passing an onLoadScript this way won't cause start()
to be run when the reload() function is run.

Add onLoad handlers to the model definitions in the Interactive JSON
to handle this issue.
onLoadScripts passed to loadModel() aren't called on reset()

Fix the reset button action by adding start() actions
to onLoad handers in the models specification.

Now pulldown components use the loadModel attribute in
their definition instead of using "loadModel('<model-id>')"
in an action.
energy2d: remove 'model' from jshint globals