source: add v56_useful which can be useful for upgrading compilers and libraries

version_54/source/v56_useful

+cmake ../ -DCfitsio_PREFIX=/afs/ipp-garching.mpg.de/home/a/aws/propagate/c/cfitsio/3.47/cfitsio-3.47/build  -DCCfits_PREFIX=/afs/ipp-garching.mpg.de/home/a/aws/propagate/c/CCfits/CCfits-2.5_cfitsio_3.47/CCfits/build/usr/local/  -DHEALPix_PREFIX=/afs/ipp-garching.mpg.de/home/a/aws/Healpix/Healpix_3.31/src/cxx/generic_gcc -DCLHEP_DIR=/afs/ipp-garching.mpg.de/home/a/aws/propagate/c/CLHEP/2.4.1.3/build -DXERCESC_INCLUDE_DIR=/afs/ipp-garching.mpg.de/home/a/aws/propagate/c/xerces/xerces-c-3.2.2/build/include -DXERCESC_LIBRARY_DIR=/afs/ipp-garching.mpg.de/home/a/aws/propagate/c/xerces/xerces-c-3.2.2/build/lib64  -DWCS_PREFIX=/afs/ipp-garching.mpg.de/home/a/aws/propagate/c/wcslib/wcslib-7.2/build/       -DCMAKE_INSTALL_PREFIX=/afs/ipp-garching.mpg.de/home/a/aws/propagate/c/gitlab/galprop/version_56/galtoolslib-1.0.855-Source/build
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