fixed: building with dune > 2.3

these symbols were deprecated in 2.3 and removed in master
allow the opm-parser test to fail

since the module currently calls the tests for cJSON and boost with
the REQUIRED flag set, cmake aborts completely even if opm-parser is
not REQUIRED. For modules which depend on opm-core that's currently a
non-issue because core has a requirement on parser, but the parser may
be useful for external projects as well, so we play nice.

Also, with this patch the config.h variable HAVE_OPM_PARSER is set...
Findopm-parser.cmake: make sure that the ERT libraries are available

and some other minor cleanups to the module. For me it still works,
but this being the build system, I can't guarantee more...
Findopm-parser.cmake: invoke FindBoost unconditionally

even if boost was found previously, it might still miss a few
libraries. thanks to @akva2 for catching this.
Disable search for Boost in parser detection

This changeset disables the effect of commit 6af17ba.  There appears
to be an unforeseen interaction between the calls to

    Find_Package (Boost)

that are implied by module 'opm-parser-prereqs.cmake' and the one
that's directly invoked in 'Findopm-parser.cmake'.  Until the
situation can be fully analysed and a complete solution implemented,
this is a temporary measure to restore the build of opm-core and
downstream OPM modules.
added: hook for conditionally compiled files

backport from opm-upscaling PR#100
Merge pull request #93 from bska/093_cmake

Synchronise build system with OPM-Core
Merge pull request #92 from akva2/fix_dune_master

fixed: building with dune > 2.3
Findopm-parser.cmake: Fix it up, next try

thanks to Arne Morten Kvarving, Bård Skaflestad and Roland Kaufmann
for the discussion.
add the boost::regex library as a prerequisite

this is required for regex-matching keywords. Once GCC 4.9 is the
minimum compiler version to be supported, this can be dropped in favor
of std::regex ...
Merge pull request #94 from andlaus/sync_Findopm-parser.cmake

Sync findopm parser.cmake
FindCXX11Features: check for a usable std::regex

and add a config.h variable in the opm-parser test.
Merge pull request #96 from andlaus/use_std__regex_if_available

FindCXX11Features: check for a usable std::regex
Use the Opm::EclipseGrid class instead of the deck directly

this has the advantage that the gazillion ways of specifying an ECL
grid are abstracted away, and thus e.g. using D{X,Y,Z}V is
automatically supported. Also, if additional grid construction methods
are implemented in Opm::EclipseGrid, these will automatically
supported by dune-cornerpoint as well. (If the API for
Opm::EclipseGrid does not change, that is.)