make the PORV test work more reliably

this seems to be a compiler bug, but it could be something
else. Anyway, using multiple functions for the tests instead of nested
scopes is probably not the worst idea anyway...
EclipseState: don't use static vectors to specify supported grid properties

this fixes a really ugly and hard to find bug if EclipseState was
instanced multiple times: The EclipseState object passed to some of
these structures was destroyed, but the arrays stayed even if the next
EclipseState object was at a different location and also could use a
completely different grid...
fix the "only <double> can be queried for NaN" exceptions

seems like some compilers don't overwrite an inline method of a
template class with its specialization. A compiler warning would have
been nice to have in this case, though...
Merge pull request #332 from andlaus/fix_nan_exception

fix the "only <double> can be queried for NaN" exceptions
Merge pull request #331 from andlaus/fix_PORV_tests_v2

Fix PORV tests v2