[release] Introduces macro for dealing with unused paramter warnings and rem

This patch introduces a new macro DUNE_UNUSED_PARAMETER(parm) for marking
unused parameters that are there for a purpose (e.g. the prescribed interfac
The macro simply performs a cast to void. In addition all unused parameter w
that I found were removed.
(cherry picked from commit 98253887c31d7501af8bee69b90996b7c59c162e)

Signed-off-by: Markus Blatt <markus@dr-blatt.de>