Feature/add in-text work citations

[johannesdewit]

Adds separate processing for links to works within descriptions which are not citations but mere mentions of the works. This is preferable to the old situation as not al links to works occur within a citation-context (see the example in the screenshots).

Features

• One can mention a work in the following forms @work_key or @{work_key}, which copies pandoc's syntax for mentions.
• A mention will create a link, and include the work title in as link text.
• Old citations of the form [[@work_key]] are processed as before.

Changes in the code

• I added an inline processor in md.py for the work mention links, refactoring a bit of the work citation code as well.
• Updated the descriptions to match the new syntax.

Example

Former:

With changes:

[andredelft]

Paar kleine opmerkingen, maar ziet er mooi uit!