general: apply consistent indentation to files

thanks to @memeplex.

Script used:

    #!/bin/bash

    modeline='" vim: set fdm=marker et ts=4 sw=4 sts=4:'

    find . -name '*.vim' | while read script; do
        [[ $(head -1 "$script") == '" vim:'* ]] || \
            sed -ir '1s/^/'"$modeline"'\n\n/' "$script"
        sed -ir -e '1s/^" vim:.*$/'"$modeline"'/' \
            -e 's/\s$//' \
            -e 's/\t/        /' \
        "$script"
    done
toc: close the TOC window after navigating by default.

this behavior is configured by *g:pandoc#toc#close_after_navigating*.
fix indenting for some stuff the script didn't catch.
folding: emulate vim's marker foldmethod.
keyboard: make the use of the * register explicit.
keyboard: make no-formatted toggle less awkward.
markdown.lists: define API
markdown.lists: implement list functions.
folding: #. indicates a list item, not a header.
folding: #. indicates a list item, not a header.
keyboard: define list navigation mappings
menu: enable and disable menu when entering and leaving buffer
markdown.lists: implement sibling navigation.
keyboard: fix mapping for PrevListItem

was overriden by mapping for CurrentListItemParent()
markdown.lists: implement children navigation
chdir: don't fail if the current dir doesn't exist.
toc: #. indicates a list item, not a header.

refers back to 0e51f2177bd157060290483b2604664c1a4735a8.

Closes issue #63.
Merge branch 'markdown.lists'