ADR Suggestion Backward compatibility

[rozyczko]

Core and technique-specific modules write/read multiple files and multiple file types.

The structure of those files may change, and an agreed-upon mechanism for reading (writing?) older versions of these files must be documented.

Proposal

Reading:

• For external file formats (like CIF), we should cover as much as possible in terms of versioning. Users' files might be written with older software but since the format is known, we should be able to read it.
• For our file formats (like json for projects), we should cover AT LEAST one API change prior.

Writing:

• All writing should be done with the most recent version of the file format