template and Latin Modern

* Introduce a template.

We've duplicated the stylistic definitions, the heading and the guideline hint far too often. Any sort of consistency became impossible. But no more. This stuff has been outsourced into a template file, now a one-stop shop for sweeping changes, should they ever be required.

* Use Latin Modern.

More or less the future of the Computer Modern fonts, Latin Modern is available in Type1 and OpenType formats. This will make font rendering far more beautiful (because Type3 font rendering is exceedingly poor in basically every PDF viewer) and should even improve copying and pasting from the documents.