Add methods to set detector offsets to StripConnection

[teozec]

This PR adds two methods to the StripConnection class (in file striptease/stripconn.py): set_offset and set_offsets: they send a SLO command to set the offsets of one detector or of all detectors on a polarimeter.

Before merging, two things need to be checked:

• [x] Is the DET{detector}_OFFS command a BIAS or a DAQ kind command?
• [x] Should set_offsets also accept numpy arrays? This is already possible thanks to the cast in the call to slo_command, but the type hint needs to be changed (meaning that numpy.ndarray has to be imported or a general "Indexable" type needs to be used - I do not know if such a type exist).

Please let me know if I should change or add something (perhaps a test?). Thanks!

[ziotom78]

Hi @teozec, thanks for the PR! Regarding DET*_OFFS, I verified that they are DAQ commands.

Regarding set_offsets, I would not bother providing the exact type for the parameter: just specify it as Union[int, List], as numpy.array can be converted from and to List (but the conversion never happens, those type hints are just hints). We use type hints mostly for documentation, and this should be enough.

[teozec]

Perfect, thanks! So I think the code is OK as it it, since set_offsets expects a List and set_offset expects a int. Let me know if I should make any changes!