--latex to support LaTeX templates

[kblomqvist]

http://eosrei.net/articles/2015/11/latex-templates-python-and-jinja2-generate-pdfs
http://akuederle.com/Automatization-with-Latex-and-Python-2

[kblomqvist]

This could be also checked from output file extension. If it's .tex, load Jinja with the above options.

[kblomqvist]

Use with ST3, http://paulklemm.com/blog/2016-03-06-watch-latex-documents-using-latexmk/