Various files have group-related doc errors

follow-up to 4 PHPDoc fixes, ironing out more warnings:

* @defgroup names should be single-word identifier, ie. [a-zA-Z_][a-zA-Z0-9_]* . no hyphens and dots.
* to group related functions in a file, use 'member groups' (@name header), not 'modules' (@defgroup|ingroup|addtogroup). latter work at a global level, creating a new page for each group - which isn't what you want for your 3 related module functions.
* a @defgroup can be defined only once (it can be added to with @addtogroup|ingroup).
* @file description must be on an extra line.

if anyone wants to help out fixing the Doxygen doc, just check the daily updated Doxygen error log of HEAD at http://drupal.kollm.org/ .