Merge remote-tracking branch 'origin/auth_getUserData_improvements'

* origin/auth_getUserData_improvements:
  KISS - remove class constants for REQUIRE_GROUPS & IGNORE_GROUPS and replace with boolean values
  use $requireGroups constants in auth classes; comments; code improvements
  fix comment errors, sp. & grammar
  code styling - add missing braces
  Allow user info to be retrieved without groups
  Restore correct public interface of getUserData() for authldap plugin

Conflicts:
	inc/common.php