Switched to locally hosted underscore
Minor interface tweaks
Refactored editor instantiation into module

Also made editor names more immediately legible. I'll extend this naming scheme
to the rest of the files in subsequent commits, but for now this file's interface
hasn't changed.
Removed jquery requirement (unused for now)
Refactored backend to use
Added require.js as dependency
Refactored server to use require.js
Fixed regression introduced while changing event names
Removed second test pane

At the moment, it's not being used and I don't like the possibility of evaling
someone else's code in a local iframe, anyway. If I can find a way to transmit
test results between browser instances without evaling code, then it might come
back. Otherwise, I think the "show your opponent's code" functionality will have
to be axed.
More element name standardizing