Clean up comments and whitespace

Clean up comments and whitespace

* Break most comment lines at 80 columns
* Break code lines at 100 columns or less
* Fix capitalisation in comments
* Fix several instances of reversed name and type in @param, Doxygen cares
* Replaced @param with @return in several places
* Use a Doxygen format list in doc comments where appropriate
* Reduced comment duplication in subclasses, for maintainability
* General copyediting of comments
* Fixed a couple of other minor code style issues

Change-Id: I3a6f9a6870a9b859c1bd4251202acba607fbf2b7