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 #162 from andlaus/sync_Findopm-parser.cmake

Sync findopm parser.cmake
implement support for the NTG, MULTPV, and MULT[XYZ]-? keywords

or rather grid properties, since they can be edited using MULTIPLY and
friends. note that the property interfaces must be extended for this
because EclipseState is not passed to the DerivedGeology class and is
not even available in some cases...