Make sliders update when sliding
Add basic widget locking.

New run isn't working to spec yet because the logic needs to be cleared up (see #28)

Partially fixes #24
Fix new run button with input locking
Tweak button toggling in response to PR feedback

https://github.com/NetLogo/Tortoise-Climate-Change/pull/24#issuecomment-35347115
Merge pull request #24 from NetLogo/24-locking-of-inputs

Locking of inputs