Add a script to remove Mendeley's bibtex keys

Mendeley has the unwanted side-effect of exporting some unwanted keys:
into BibTeX files: file path, abstract, and user notes. This script
passes over a BibTeX and filters these keys in-place. Example usage:

    $ cleanbib refs.bib
    wrote 14 entries.
Don't import common makefile to toplevel

This causes the linter to try to pass the build system generated
config.h file, which fails.
LaTeX build system overhaul

This revamps the LaTeX compilation process so that it supports global
BibTeX libraries, and filtering unwanted Mendeley keys. A rather large
changeset that also incorporates a refactoring of all LaTeX compilation
logic into the Makefile.latex file.
proposal: Keep a local copy of needed references

Rather than relying entirely on a large Mendeley-managed bibtex file
which isn't tracket in this repository, pull out the required citations
at compile time and store them in a locally tracked refs.bib file, to
support building with or without the library bibfile. If the global
bibfile isn't present, use the local version.
docs: Add 'summary' to list of subdirectories
summary: More twiddle and verbal diarrhoea
proposal: Don't use a separate cover sheet
summary: Re-order and cull (some of) the crap
log: Add notes for Monday
summary: Polishing up a turd