Configurable groups for input

[cwilling]

We have ready for next release some predefined groups that can used as input, rather than having to itemize some large list on the command line, using the new -g|--group option. The groups that HooRex know about are all the SBo software categories (audio, libraries, system etc.) as well as the "all" group i.e. everything in the repository. So 'hoorex -g desktop' means to use all the package names in the desktop category as input.

The predefined groups are probably more cute than useful; what might be really useful is if the user could define their own groups e.g. 'hoorex -G mine="abc uwh kfj ... jfdh" in which "mine" would be the group name and abc, uwh, kfj, some more pkgs and jfdh would be the package names in the group. We could save that in the user's configuration so they could always run "hoorex -g mine" to process all the packages in the mine group.

Or, is it sufficient that since we can have package names taken from stdin, the user could just make a file with the packages of interest and then do "hoorex < package_list_file.txt"?

[cwilling]

In fact, already regularly using hoorex -l1 $(cat sbos_to_rebuild.txt)