Added example multi-line indented block
Spelling and markup
More code markup
typographic fixes
Merge branch 'gh-pages' into thw-indentedcblock

Conflicts:
	lessons/thw-python/flow-control/python_flow_control.ipynb
	lessons/thw-python/vars-types/variables.ipynb
Merge gh-pages into wltrimbl-thw-indentedcblock
merging in gh-pages