remove safeguards preventing high-order remeshing, so we can start testing the new implementation (cf. #572)

install LibreOffice + computer modern fonts so that we can automate the creation of the tutorial docs

if the surface is later transformed (fixes #566)

- moved renumbering calls to GModel, so that renumbering is also performed when modifying the mesh interactively (e.g. after clicking on "order 2" in the GUI)
- handle order 1 in setOrderN

Uvw

See merge request !264