Add error message when assembling point integrals rather than silently
returning zero.
Merge branch 'johanhake/fix-absolutetolerance-pointintegralsolver'
Merge branch 'mliertzer/fix-issue-361'
Add test for intersecting manifolds contributed by David Bernstein.
Revert "Add test for intersecting manifolds contributed by David Bernstein."

This reverts commit 5909302726033fdb50be6296a362723c756162f1.
Add test of intersecting manifolds again, now hopefully running in
parallel.
Merge branch 'meg/test-intersecting-manifolds' into next