(DRAFT) CIF writer - metadata from NeXus to Analysis

[celinedurniak]

EasyDiffraction will use CIF format to store metadata related to the experiment.
This issue lists the metadata from the NeXus file to be stored in the reduced CIF files and used in the analysis

• instrument name: in entry/instrument/name
• facility name: not yet stored in the NeXus file
• start time: entry/start_time
• end time: entry/stop_time

Info about date and time format in CIF: https://www.iucr.org/resources/cif/spec/ancillary/datetime

Message from @AndrewSazonov:

I couldn't find any keys to describe the start and end date and time of the measurements in coreCIF. So it looks like we need to come up with our own names. The diffrn category from coreCIF looks like a good candidate for adding new keys, as it is the category of data items used to describe the diffraction experiment. We can then use the datetime_initiated key from pdCIF, which specifies the date and time when the measurement started. Finally, we can extend it with, for example, datetime_completed. As a result, we get:
diffrn.datetime_initiated and diffrn.datetime_completed. And we should stick to the format given in your reference.

For the sample, there is only name in the NeXus file for DREAM. Waiting for input from ECDC (Jonas Petersson)

Note that the reduced file should contain other types of metadata, like difc, twotheta... But they will be calculated during data reduction. Therefore their storage will be requested in a different issue.