Note: There is quite a difference between markdown and doxygen.
Therefore, changing the introduction will now mean editing two files.

in the case of ALBERTA-refinement it is necessary to communicate
3 levels of refinement per face, as a single element refinement
may induce a triple refinement of a face.

Add missing include

See also bug #1.

See merge request !1

it now exploits the fact, that refinement calls are boolean
due to the recursive nature neighbours may be assigned at the wrong time
which in parallel leads to wrong face refinements.
this is caught by returning false and the refinement is
initiated again.