"merge" python tools

[goerlibe]

our tool suite is growing larger and larger, now we have 6 entry points defined in setup.py.

We could "merge" them into a single discopop tool similar to the git command line interface which has a single git tool where the first argument defines which subtool to run (git commit, git rebase, ... ==> discopop profile, discopop explore, ...) .

Argparse has a feature where you can define subparsers (argparse subparser example) so it should be quite easy to implement.

The only downside I can think of: bash will not autocomplete when pressing tab. (possible solution for autocomplete which could actually be a really nice additional feature on its own, but it seems kind of an extra hassle to setup)