[tex-live] TL version info

[Karl Berry]

FYI, I've changed texconfig so that it looks for
<TLROOT>/release-texlive.txt (in addition to the tetex release-* files),
and prints its first line.  The output looks like this:

texconfig version 1193182750
TeX Live version: development (see http://tug.org/texlive)

I added the file in the svn source, and will arrange for the images to
include it (at the top level).  The installers will have to copy it to
the runtime.  


I also updated texconfig help, and added a new option
texconfig version (or --version), to just print the version info.

Incidentally, I also updated the updmap help message a few days ago.

Comments/suggestions welcome.

karl