linting for #541; old renderer code worst culprit and is mostly TODO

Conflicts:
src/define.js
src/extensions/layout.arbor.js
update readme for testing & linting
formatting
move watch
revise targets
clearer indentation
consistent capitalisation
clean lint; closes #541

Conflicts:
	src/extensions/layout.cose.js
mapLayout() => mapLayoutData() in docs; closes #540
Link to user demos; closes  #539
Link to Cytoscape desktop on top of docs; closes #542