add optional #:note to 'bib-entry'

[bennn]

Add an optional argument to bib-entry to typeset a comment directly after a citation --- with no punctuation between the end of the citation and start of the comment.

Example uses:

• making an annotated bibliography, with an element that appears just below each citation

• adding "accessed" dates just after a URL, e.g. (bib-entry .... #:url "...." #:note ", accessed 2018-06-14")

Example document:

#lang scribble/manual
@title{Doc}

@(bibliography
   (bib-entry #:key "WT18"
              #:author "J. Wang and S. Z. Taylor"
              #:title "Parabolic Monoids and Concrete Galois Theory"
              #:location "Mathgen"
              #:date "2018"
              #:url "http://thatsmathematics.com/mathgen/"
              #:note ", accessed 2018-06-14")
   (bib-entry #:key "RJ18"
              #:author "D. Raman and R. A. Jones"
              #:title "On the Computation of Equations"
              #:location "Mathgen"
              #:date "2018"
              #:note @elem{@linebreak[]@linebreak[]@emph{Abstract:}
                Let @math{f_Z = U} be arbitrary. In @cite{WT18} the authors
                address the locality of hyper-holomorphic planes under the
                additional assumption that @math{Θ' = -1}. We show that there
                exists an one-to-one, stable, invertible and differentiable
                real, super-conditionally complete subset.}))

Output:

[LeifAndersen]

Honestly, accessed seems like it should be its own field. Like:

:accessed "..."

Because that will very from style to style.

[bennn]

Leif is right, putting ", accessed" in a note is a bad way to add that information. I can remove that example from the commit message.

I'm not sure now whether the note should come directly after the citation, or have 1 linebreak in between. (My preference is for putting it directly after.)

[bennn]

Added a history annotation and updated the commit message.

To be clear: #:note @elem{....} sticks the elem at the end of the bib-entry.

If there are no comments, I'll merge this next week