update #14
 - simplify reduced basis space class, no longer follow functionspace
 construction but directly derive from model functionspace
 - in UseCRB make sure geo files are installed (@StephaneVeys: it should fix your problem,
 heat1d.geo was not installed in the bindary dir)
 - fix test_rbspace compilation
 - added meta namespace and Pch template class in it to provide the return type
 in a consistent way