The old way via `GET /count?uri=...` still works, but is now deprecated
and might be removed in future releases.
The new way is much more efficient especially fore multiple listings.
The internal implemention is improvable though.
This commit introduces a new configuration section [markup] to refine
Misaka's Markdown extensions (by default strikethrough, superscript and
autolink).
Furthermore, you can set custom HTML elements/attributes that are
allowed, e.g. to enable images, set
[markup]
allowed-elements = img
allowed-attributes = src
The refactorization separates HTML sanitization from Markdown -> HTML
and allows to include new markup languages such as BB Code or
reStructuredText.