The macro name isn't all that descriptive, suggest something like:
By convention, #ifndef NDEBUG is used instead of checking for _DEBUG.
Please leave unrelated function renaming out of this PR.
Scripts may use tagging, please use existing flags instead of changing how tagging is done.
Other option would be to find a better generic terminology covering that whole area, but 'Import' is already taken for external formats...
For more generic naming, including the term blend…
From looking into this it seems likely something has one or more files open within the extensions directory that causes removal to fail.
Even if Blender has permissions to delete the directory,…
The functionality seems fine, however this will call the region_extend BMesh operator multiple times, please make the repeat argument part of bmo_region_extend_def, so the action can be implemented in bmo_region_extend_expand & bmo_region_extend_contract.
This will perform multiple reports when multiple meshes are in edit-mode, this kind of change can probably be moved into it's own PR.
It'd be interesting to know if script authors would find it useful to separate: link & append.
The name seems a bit off, it can't be items because of naming collisions with Python, but the array suffix is also a bit odd (as this is a collection).
It looks like this shouldn't be treated as a flag based on it's use elsewhere.
In RNA we don't typically call these flags as that relates to bit-masks which don't make sense when called from Python, suggest options as we have for bpy.types.Operator & bpy.props.*.
The linked_appended_* prefix reads poorly to me. We could just call this id ? (it looks to be the primary ID which would be referenced), other ID's can be clarified with longer names.
Instead of exposing all of these in one collection, we could expose them by type, similar to Main & library linking/appending API's.
Could call this name & type ? (the id_ prefix seems a bit redundant).
Prefer filepath for consistency, making it clear this isn't related to other kinds of paths.