General upkeep and updates to datalad-neuroimaging + compatibility with datalad-metalad

[jsheunis]

I'm interested in spending some time on general maintenance of this extension, and eventually updating all of the extractors to be compatible with the first release of datalad-metalad. This interest comes mainly from the need to support a seamless pipeline for metadata extraction and catalog generation. Based on our current user profile, supporting metadata extraction and catalog generation for neuroimaging data seems very applicable.

There are a bunch of open PRs, some quite old. I'll start by commenting on them and asking applicable contributors for input if needed to merge/close. I'll do the same with open issues.

At some point, perhaps in a dev call, we should probably discuss if a coordinated release is necessary, and how to approach it if so.

@datalad/developers comments welcome, and please let me know if you have other/better ideas for approaching this.

[mih]

As expressed elsewhere, I think the current approach to aligning with the current extension template setup makes most sense as a first step.