[Feature] Commenting - export of comment DB in human readable file

[zeigerpuppy]

Currently when syncing a document or repository with comments, the comment anchors are included:

a line with a comment <!--comment:OLH44TkwcO-->

These comments are referenced in the comment DB.

It would be very useful to also be able to export the comment DB into a human-readable comments list (or even include it automatically in a file, for instance .comments in the repository).

This file could be used offline to reference any comments in the documents.

Proposal

1. parse the comment DB with the comment threads and comments listed by ID
2. allow exporting this file.
3. optionally, include this in the repository as a file that is synced during git commits, suggested name /.comments

Optional

• allow bi-directional use of the .comments file. This would allow populating the RefMD database from a repository when it is imported. For instance, if a repository has been archived but is re-imported into RefMD