Added SgFieldColor2.linkField(), fixed validate bug "id","type" fields

Exposed the ability to retrieve the link field name that a color2
field references.  SgFieldColor2.linkField().  This will return
"pipeline_step" for Task and "project" for Phase Entity types.

The UserFields for "id" and "type" were not updated with the new
validate arg "forReal" which broke the ORM.
Added new event log functionality for Entity and Field classes

- SgEntity,SgField lastEventLog() and eventLogs() functions now accept
  an argument "sgFields" for specifying the fields to fill for thier
  returned result.

  Also refactored lastEventLog() as it was duplicate code.

- SgField added new functions lastModifiedInfo(), lastModifiedAt(),
  and lastModifiedBy().

  It is now easy to retrieve the user/time of the fields last
  modification with these functions.