Doxygen tasks

[Gedare Bloom]

Here are a few ideas for GCI tasks. If no one has objections we can
try to get them set to go.

* Convert function @brief from "Table of Contents" to "Topic sentence" style.
* Replace @a with @param.
* Replace @return with @retval statements.
* Put all @{ for @defgroup, @name statements in the same comment block
as the defgroup/name statement.
* Ensure all @{ have matching @}
* Identify what @ingroup do not have a @defgroup
** Add defgroup for the missing ones

-Gedare