Implement speed-up for the case of a drawn way intersecting with another way. Do...

Implement speed-up for the case of a drawn way intersecting with another way. Do this by not highlighting nodes that are offscreen. Added a bit of extra logic to make this happen, like tracking the "highlighted node" state of a way, and updating nodes when appropriate. I suspect I missed a much simpler way of doing this, in the UpdateEntityUIs logic somewhere...

Also a bunch of ASDoc documentation.