Updated: Replaced :Rename with vim-eunuch.
Updated: Replaced some of my options with tpope/vim-sensible.

This is an experiment. Maybe I'll revert this soonish. Let's see.
Implemented: Make all *.tex files be handled as LaTeX.
Implemented: Auto-adjust initial RST heading length.

Inspired by UltiSnips shipped RST plugin.
Implemented: Automatic creation of RST headings.

Just create the first over-/underline char and type the heading. Also
works for editing existing headlines. /cc @beberlei, @kore