Move all Doxygen-to-Docbook rules into a single transform, remove redundant rules/transforms and add support for verbatim and linebreak elements.

git-svn-id: http://lufa-lib.googlecode.com/svn@2729 d5102386-fcda-11dd-9fdb-3debd5008f28
Tweak HV1 help styling and image elements.

git-svn-id: http://lufa-lib.googlecode.com/svn@2730 d5102386-fcda-11dd-9fdb-3debd5008f28