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 c467304.  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 #116 from bska/116_cmake

Synchronise build system with OPM-Core
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 #117 from andlaus/sync_Findopm-parser.cmake

Sync findopm parser.cmake
ParserAdditions: Catch up to method rename

Commit OPM/opm-parser@ca1733cc renamed the method

    Parser::addKeyword() to Parser::addParserKeyword()

Catch up to that renaming to fix the build of opm-upscaling.
Merge pull request #118 from bska/fix-build

ParserAdditions: Catch up to method rename
FindCXX11Features: check for a usable std::regex

and add a config.h variable in the opm-parser test.
Merge pull request #119 from andlaus/use_std__regex_if_available

FindCXX11Features: check for a usable std::regex
use extended regular expressions in the test for std::regex

for some compilers (e.g., GCC < 4.9) the default is buggy and
opm-parser thus uses extended expressions...

thanks to [at]bska for digging this up!
Merge pull request #120 from andlaus/test_for_extended_std__regex

use extended regular expressions in the test for std::regex
add RUNSPEC sections to the GRDECL files

actually these should be moved to the .DATA files, but since they do
not exist, let's add them to the grid definition files in the
mean-time.
Merge pull request #123 from andlaus/add_RUNSPEC_to_GRDECL_files

add RUNSPEC sections to the GRDECL files