Change how publications associate with a project

[keelinm]

Currently when a project page is created, the publications (bibkeys) associated with that project must be added to that project page, and members have to remember whenever they have a new publication to (not only add it to diag.bib, but) separately add it to the project page. Ideally the project should have a project-tag which could be mentioned in the diag.bib entry. The publications list for the project would then update automatically when the diag.bib had a related publication added.

One issue is that retrospective fixes would be needed. I think there are 2 ways to handle this:

1. We allow projects/publications to be connected both the old way and the new way (so a bibkey in the project page, or a project-tag in the diag.bib)
2. We make a script to go over the project pages and add the bibkeys mentioned in them into the related diag.bib entries

[JoeySpronck]

Approach to solve:

1. in bibparser: make a function that returns a list of all project names
2. in bibparser: make dict with key project names and value list of related bibkeys/publications --> save as json
3. in bibloader (in plugins): load this json and make a new variable that can be accessed via pelican (use signals: generator function)
4. in the projects-single template: access the pelican variable and fill the bibkeys in the project template