WIP: Feature/mixed space

Migrate from dune-fufem to dune-functions bases in film-on-substrate.cc:

• the basis is now assumed to be a compositeBasis of two powerBases (dune-functions compatible and dune-elasticity compatible)
• implemented a geodesicfeassemblerwrapper.hh that transforms the assembled matrix and gradient from the mixedgfeassembler to the combined form so the riemanniantrustregionsolver can still be used
• the mixedriemanniantrsolver can now be used (also with 2 different orders for rotation and deformation)