Code style & docs.
Code style cleanup.

Lots of code style cleanup, would like review on the following points
especially -

* Removal of CiviCRM copyright statements. Should these be included?
* Move of civicrm_entity_enable() to .install.
* Small changes to civicrm_entity_rules_event_info() for easier reading.
* Minor changes to civicrm_entity_action_load_user() to separately load
domain ID. (Cache this statically to reduce lookups?)
Merge pull request #14 from xurizaemon/7.x-1.x-code_style

7.x 1.x code style