[release] Add a cpp flag to config.h if psurface is found in at least version 2.0

With this flag (which will not stay forever), I can enable the hdf5 functionality
of psurface-2.0 when it is available.
[release] Allow reading of psurface objects from hdf5 files

... if a new enough psurface is available.
Merge branch 'master' of https://git.dune-project.org/repositories/dune-grid