GenericEntityCRUDController

NOTE: Untested, has no tests, and is generally untested without any tests. :-)

Fills some of the gaps in Drupal 7's entity CRUD implementation. Turns DrupalDefaultEntityController into a much better factory for entities. Exposes create, save/update, and delete, and lets you define your own hook API.

Uses NealB's entity example as a starting point, refactors lots of code from node.module, and was inspired by this issue: #893842: Entity example module.