Magic Book 1.2

Probably the last version for a while. Thanks for the suggestions reddit.

* Cleaned up the entire command with tab stops, which the command blocks won't parse.
* Added a "clear" section to eliminate stray entities and reset scoreboards.
* Moved the "summon" section back farther in the book. Added summons for Elder Guardians, Ender Crystals, Giants, and the Killer Rabbit.
* Added a "credits" page to the back of the book, with a link to the gist.