Easily compress/decompress itsdb profiles

[goodmami]

PyDelphin has no trouble reading or writing compressed (.gz) files in [incr tsdb()] profiles, so a nice feature for the delphin command would be to compress a profile in-place. Perhaps this could be part of the mkprof subcommand. This could be done just by adding an --in-place switch to alternate with the otherwise required --source:

delphin mkprof DEST (--source PROFILE | --in-place)
                    [--apply=APL]... [--filter=CND]...
                    [--relations=FILE] [--full|--skeleton] [--gzip]
                    [-v...|-q]

Then to compress:

delphin mkprof path/to/profile --in-place --full --gzip

To decompress:

delphin mkprof path/to/profile --in-place --full

But this could also be simpler, e.g. something like:

delphin mkprof path/to/profile --compress
delphin mkprof path/to/profile --decompress

But then we'd need a new usage synposis and 2 new options, instead of just one new option.

[goodmami]

Going with --in-place, because then other things open up, like filtering or applying to profiles in place.

Creating skeletons with --in-place is currently not allowed, because deleting the non-item tables (e.g. without deleting extra files in the directory) is a bit messy, and it seems a weak use case anyway.