add support for OpenBLAS as toolchain lib for linear algebra
add support for goolf toolchain
fix Lapack import
no BLACS in goolf
allow empty list of BLACS modules
also define list of MT BLACS libs empty, and handle that properly
add update to custom legacy ConfigurationVariables
change call of _action_taken
Merge pull request #558 from stdweird/fix_legacy_prefix

fix 2 important bugs in configuration parsing
Merge branch 'develop' of github.com:hpcugent/easybuild-framework into develop
Merge branch 'develop' into fix_config
Merge branch 'develop' of github.com:hpcugent/easybuild-framework into develop
add unit tests for default (and legacy) configuration
oldstyle defaults test
Merge branch 'develop' into openblas
config unittests
fix bug in repohandling
undo 'fixes', proper fix was done by #558
style fixes
Merge branch 'fix_legacy_prefix' of github.com:stdweird/easybuild-framework into fix_legacy_prefix