Add Behavior Options test to test/visual.html #test

Also clarify README subsection, seeing as the behavior options described
in that section are disjoint with the ones tested by this new visual
tests section.
Add leftRightIntoCmdGoes: 'up'/'down' option
Merge branch 'dev' into feature.leftRightIntoCmdGoes

Conflicts:
	test/unit/publicapi.test.js
	- api.spacebar #245 appends 'spaceBehavesLikeTab' suite
	- feature.leftRightIntoCmdGoes appended 'leftRightIntoCmdGoes:
	  "up"/"down"'
Merge branch 'feature.leftRightIntoCmdGoes' into dev