[lltx] mkluatexfontdb -> fontdbutil

[Karl Berry]

Hi Elie,

1) Why do you need to rename it?  What's wrong with adding the features
to it under its existing name?  Just because it will do other things?

2) If you use argv[0] to change the behavior, please also make cmdline
options to control it in the same way.  It's trivial to do that, and
that way, users can use an alias or their own trivial wrapper script to
get the behavior they want with the name they want, which turns out to
be surprisingly useful in all kinds of unforeseen situations.

3) I definitely think "lua", at least, should be in the name.
"fontdbutil" doesn't give any clues -- there are endless numbers of
fonts, databases, and utilities in the world, after all.

What are the features you want to add?

Thanks,
k