Merge remote-tracking branch 'origin/master' into core

Conflicts:
	docs/3d.html
	docs/dictionary.html
	docs/extensions.html
	docs/faq.html
	docs/gis.html
	docs/headings.html
	docs/hubnet-authoring.html
	docs/hubnet.html
	docs/interface.html
	docs/modelingcommons.html
	docs/netlogolab.html
	docs/programming.html
	docs/requirements.html
	docs/versions.html
	extensions/gogo
	headless/src/test/org/nlogo/headless/AbstractTestModels.scala
Merge remote-tracking branch 'origin/core' into headless