Merge branch 'build-tetrahedron-refrules-into-library' into 'master'

ref:staging/dune-uggrid The TET_RULESET compile-time option could be used to
load tetrahedron refinement rules from RefRules.data, however this requires to
locate the file at run-time. This was too inconvenient.

Instead generate RefRules.cc from RefRules.data including the refinement rules
and use that.

See merge request [!134]

  [!134]: gitlab.dune-project.org/staging/dune-uggrid/merge_requests/134