merge
[functions.ESV2007] fix warnings
[functions.checkerboard] fix warnings
[stuff.grid.search] remove unused variable
[stuff.la.solver.istl] disable warnings
[functions.ESV2007] use UNUSED_UNLESS_DEBUG
[functions.checkerboard] use UNUSED_UNLESS_DEBUG
Merge branch 'master' of http://users.dune-project.org/repositories/projects/dune-stuff

Conflicts:
	dune/stuff/functions/ESV2007.hh
	dune/stuff/la/solver/istl.hh
[common.ranges] updated dune-fem includes