Sort TeX template by packages (and rename)

TeX tends to produce a menagerie of auxiliary files--a habit proliferated by its various packages. Since not all projects will use all of the packages, it seems more convenient to group them by package rather than alphabetically. This is especially true because most of the files are not human-readable so it can be hard to deduce where they came from or if they are needed. The packages are centrally available in [CTAN](http://www.ctan.org/) so it still makes sense to include these rules in the template for commonly-used packages.

  * Also fixes #695 since that PR got a little messy
  * Points out why ignoring pdf and (e)ps files might be a bad idea, but gives the option anyway (cf. #602)
  * Renames the template to TeX since it is useful for ConTeXt, luaTeX, XeTeX, LaTeX, etc. which are all implementations of/extensions to plain TeX