docs updates, phantom support for automatic demo screenshots etc

Node linkout demo #584
Clarification of ready event #591
Replace live demo thumbnails with cached ones on build #587

Conflicts:
	documentation/md/core/init.md
	gulpfile.js
fix bugs etc for 2.2.9

Zoom bounds not respected on pinch #598
Improve thresholds of three finger swipe box select #596
Edge selected on touchmove pan #601
iPhone bottom browser bar disturbs position offsets on docs #595
Drag layer elements not cleared on pinch #594
Extensions download on main docs page #590
Clarification of ready event #591

Conflicts:
	documentation/docmaker.js
	documentation/index.html
	src/core-viewport.js
demo screenshots active
fix pkgver