[tex-live] updmap diagnostics

[Karl Berry]

Norbert and I have made some changes to updmap to try to help the
unending stream of confusing reports about it.

1) the very first time updmap (as opposed to updmap-sys) is run, there
is now a warning/explanation that you have to use updmap henceforth;
i.e., updmap-sys will have no effect.

2) if the files updated by updmap or updmap-sys do not match actually
used by the programs (as found by kpsewhich), a warning issued.  For
example, if updmap is run and then later updmap-sys is run.

Various small other doc/diagnostic tweaks along the same lines.

No changes to the functionality intended.

I won't be surprised if there are unexpected results, so let us know.
When it comes to updmap, the unexpected is to be expected.

Best,
karl