trying tlcritical (verification error cleanup)

[Karl Berry]

Hello TL - Norbert has made some changes to tlmgr to provide more
specific error messages when verification fails. They are in tlcritical
now. We would dearly like to have some more testing before we push this
out to the world. 

So if anyone is up for trying tlcritical, please do, and let us know.

The issue isn't so much the new error messages as making sure the
non-error cases, which are the vast majority, still work. So don't worry
about trying to exercise the new stuff, just do what you normally do and
make sure it works.

There are no other notable updates in this tlcritical round.
--thanks, karl.