adds new version and one new chapter
add custom rendering chapter
fix issues with Markdown incompatibilites
mention touch area expansion and passing touches on in responder chain
chapter on grids; mention multi-drag
fix missing word
include reference to shader cookbook
updates to physics in SB chapter
chapter on spritebuilder-joints by kevin karol
removes image subcaptions
merge both joint chapters
update index.json to use 1.1 version of joints chapter
minor markup fix