Spatial Partition Edits v1

Initial round of edits--still have outstanding questions.
Spatial Partition Edits v2

A few more edits!
Merge remote-tracking branch 'upstream/master'
Spatial Partition Edits v3
Merge branch 'master' of git://github.com/laurenbee/game-programming-patterns into laurenbee-master

Conflicts:
	book/spatial-partition.markdown
	html/spatial-partition.html