split api.Camera off from api.Observer

improving separation between 3D world and 3D view related stuff and
2D-only stuff
make bin/cloc.sh use cloc on path instead of downloading it

I think the way I had it set up before was because Homebrew didn't
have cloc yet?  anyway, it definitely does now
upgrade to sbt 0.12.3
Merge remote-tracking branch 'origin/5.0.x'
put back a method I'd mistakenly thought was part of 3D stuff
Merge remote-tracking branch 'origin/master' into core

Conflicts:
	bin/cloc.sh
	headless/src/main/org/nlogo/agent/Camera.scala
	headless/src/main/org/nlogo/api/Observer.scala