Fix buf in DofMap::dofs().

Not sure whether it should return globals DOFs
but definitely it was uncorrect before.
Slight optimization of DofMap::dofs()
Fix typo in DofMap::dofs()
Get rid of unnecessary cast in DofMap::dofs().
Merge branch 'garth/fix-numpy-64-bit-int-wrappers'
Merge branch 'chris/spellcheck'
Merge branch 'blechta/fix-issue-342' into next
Merge branch 'cilix/improve-periodic-bc-demo-doc'
Only add X11 include dir and libraries to PETSc variables on OS X when X11 is found.
Merge branch 'johannr/petsc-x11' into next