Revert modifications from rpms/group/development (must match RH definition, in fact matching EL6 definition presently...)
Add nedit to the list of standard editors
Add libXScrnSaver to interactive servers
rpms/document-viewers: add xdvik
rpms/development-base-tools: add python-devel and openmpi
(also remove inappropriate gcc and cmake version)
Merge pull request #60 from jouvin/el7.x-misc

sl6.x: various package group added/adjusted