MD2D property setters and getters don't set closure variables

[rklancer]

In several cases, a closure variable like temperature or viewRefreshInterval is used in modeler.js to maintain state.

However, the property setters for these properties don't affect the closure variable actually used by the code. Instead they only set a member of the properties object.

For example:

> model.set({temperature: 100})
> model.get('temperature')
  100
> model.temperature()
  300