Mention `org-mode-reader' for Haunt in README

Enable customization of where rendered documents are written to

Lint package

Only handle `:haunt-metadata' when present

Add option for extra haunt metadata per file

Hello,

Thank you for making ox-haunt.el. I use some extra metadata to control
how my haunt website is organized. I modified ox-haunt to let me add
extra metadata to each file. Like this:

#+haunt_metadata: ((recent . t) (status . "Completed") (purpose . "Make
development with GNU Guix easier."))

Do you consider this a worthwhile feature? Does this change look
alright?

Best,
Tassos Manganaris

Add 'Users' section to README.md

Add: support for single org-mode file flow

Changes implemented:
 - When using the subtree only flag in org-export, export the current
   subtree after checking if it or any of it's parents have the
   "EXPORT_FILE_NAME" property and that it is marked as DONE. Then parse
   title from heading, date from CLOSED or SCHEDULED state and tags from
   org-mode tags.

 - Add "A" binding in org-export UI to try and export all valid
   subtrees in current buffer.

 - Expose HAUNT_IMAGES_DIR as variable that handles where link images
   are to be saved.

Prefer 'substring' to 'cl-subseq'

Fix propagation of `dest-path' in `ox-haunt-export-as-html'

Update docstrings

Update Package-Requires

Update README.md

Propagate `:haunt-base-dir' if set as a buffer-local custom.

Remove `html-tidy' support.

Implement a 'ox-haunt-base-dir custom variable

Remove replacement for 'ox-html-src-block

Add recognition for the TAGS keyword

Rename vestigial ':hugo-base-dir

Add replacement for 'ox-html-src-block

Stop wrapping output in <article>

Wrapping the exported HTML in <article> is just a hack. I've submitted a
patch for 'html-reader, which properly solves the issue.