[Buildsystem] Fix naming of build system variables in adaptivity/
[Adaptivity] Remove broken file adapt.hh

adapt.hh has been broken since the move to the new backend
infrastructure, no use in dragging it along anymore...
[Cleanup] Remove deprecated container access methods in matrix and vector views

The removed methods were never part of an official release, so don't
introduce them into one at all when they are already deprecated.
[Cleanup] Remove broken file backend/vectorutilities.hh

Another file that hasn't survived the backend transition...
[Cleanup] Remove broken files gridfunctionspace/debug.hh and gridfunctionspace/dofinfo.hh
[Cleanup] Remove broken file gridfunctionspace/printvector.hh
[Cleanup] Fix naming of header guard in constraints/common/constraints.hh
[Constraints] Move NoConstraints to constraints/noconstraints.hh

Having the empty constraints implementation in
gridfunctionspace/utility.hh isn't very intuitive, so this patch moves
it to a new header noconstraints.hh in the constraints/ folder. I've
kept the old file with a deprecation message, but most users probably
won't notice because the file was automatically included for them by
gridfunctionspace.hh.