fix Lmod version parsing for rc's, bump required Lmod version to 5.2, get rid of (slow) for detecting module dirs, set $LMOD_IGNORE_CACHE
clarify comment w.r.t. $LMOD_IGNORE_CACHE
remove uneccesary import statements for md5/sha that produce deprecation warnings
Merge branch 'develop' into lmod_5.2
Merge pull request #780 from boegel/lmod_5.2

fix Lmod version parsing for rc's, set $LMOD_IGNORE_CACHE, bump required Lmod version to 5.2, get rid of (slow) for detecting module dirs