Conflicts:
	dune/xt/common/test/float_cmp.cc

You now have to write
```
DXTC_has_typedef_initialize_once(Bar);
```
instead of
```
DXTC_has_typedef_initialize_once(Bar)
```
which makes it easier for some tools to digest this piece of code.

refs #4

However, `DynamicVector` does not have `standard_deviation`, so this is
currently disabled.