Document for review: evaluation order and state tokens

As part of trac ticket 9390[1], Simon PJ recommended that we try to get a document written that clarifies some of the issues regarding evaluation order, and get it included in the GHC wiki. After a few iterations with review from Simon, I've got a first "publicly consumable" version available at: https://www.fpcomplete.com/user/snoyberg/general-haskell/advanced/evaluation... I'd appreciate any feedback on this document before I add it to the wiki. Michael [1] https://ghc.haskell.org/trac/ghc/ticket/9390