'darkzen' color profile for HTMLs generated by mdvimb

Get current version at https://netvor.info/scripts/mdvimb

Work around, obey, or disable.

Mostly for easier visual distinction and also for fun.

'x' meaning primary, 'xx' meaning 'C-C' and 'v' meaning vipe(1).

...for the love of podcasts!

Many files may look like text file but be actually considerd binary by
git.  In suich case this setting can be extremely confusing.

Most notably, add example of Vim configuration needed for the function
to work.

How come I haven't set this years ago?

http://unix.stackexchange.com/questions/72131/detecting-x-session-in-a-bash-script-bashrc-etc/338862#338862

Hardly needed to do repeatedly and when it is, it's best linked with
an observed command on the same line.

I keeo forgetting to say "modify" and even `m` alias did not help.  This
maybe...