Handle dot in metadata key name

[karlicoss]

So I ran into a need to filter metadata key containing dot, which interferes with the way the key filter is specified in git .config file, since nbstripout uses dot as nestedness seprarator. Sadly, I don't control the key names either, they are coming from EIN Emacs plugin and seem to be hardcoded.

For now I just hacked nbstripout to treat dot as part of key name, but that's of course not a proper fix. Thought for a bit, but couldn't come up with a good backwards compatible solution for specifying keys containing dots, so at least leaving this issue here...

[kynan]

Sorry for the late reply. One potential option I could see is specifying metadata keys as lists instead of dot separated strings. That's a bit of effort when also trying to maintain backwards compatibility. Given that JSON keys also cannot contain dots I think lobbying for your plugin to change their metadata seems like a better solution.

Let me know what you think and if you're still facing this issue.

[kynan]

This is the same as #143, which has been addressed in #144. Please reopen if that doesn't resolve your use case.