This allows code such as
```
if (dim == 1)
  DUNE_THROW_IF(order > 5, ...);
else
  DUNE_THROW_IF(order > 3, ...);
``

Move suitable default to type_traits, use in Abstractions

Move is_vector and is_matrix to type_traits.hh

Extend Matrix/Vectorabstractions

# Conflicts:
#	dune/xt/common/fvector.hh

Deprecation stuff and things

closes #53

closes #13

This reverts commit e54351e2.

It would be better if we could move classes only with
deprecation warning in place for a while.

Dailywork timkeil

[ci] adds testing on arch docker

 remove last dune-fem compat code

revert_threadstorage_update

This reverts commit 061f0659, as we
decided against this in dune-xt-grid (see the imaginary protocol in our
heads).

Dependencies updates

since xt-la depends on xt-common and dune-istl, we can just depend on
istl here too