The use of absolute paths is now enforced when calling
`notmuch_database_{open, create}`.
+New function `notmuch_directory_delete` to delete directory documents
+
+ Previously there was no way to delete directory documents from the
+ database, leading to confusing results when the "ghost" directory
+ document of a renamed or deleted filesystem directory was
+ encountered every time the parent directory was being scanned by
+ `notmuch new`. The mtime of the old directory document was also used
+ if a directory by the same name was added again in the filesystem,
+ potentially bypassing the scan for the directory. The issues are
+ fixed by providing a library call to delete directory documents, and
+ deleting the old documents in `notmuch new` on filesystem directory
+ removal or rename.
+
Database revision tracking
Revision tracking is supported via a new prefix "lastmod:" in the