Merge branch 'master' into trilinos

Conflicts:
	nutils/topology.py
Merge branch 'trilinos' of https://github.com/nutils/nutils into trilinos
add cache flush/info
Merge branch 'master' of https://github.com/nutils/nutils
Merge branch 'trilinos' of https://github.com/nutils/nutils into trilinos
Merge branch 'master' into trilinos