pythonds edits chp 1
chapters 1 and 2 edits
edits to first 3 chapters:references to figures and activecode and listings
one more curly brace problem
recursion edits
edits to searching sorting trees
graph edits
Merge branch 'master' of github.com:ranum/runestone into ranum-master

Conflicts:
	source/BasicDS/stacks.rst