[mythtv] minor mythweb update

[Chris Petersen]

Well, I finally found some time to get to one of the most oft-requested
updates to mythweb:  custom date formats.

I created a section in the settings to let users set most of the date
formats throughout mythweb (please let me know if I forgot something). 
I removed the longdate_format variable from the config files (which
means that the "compact" theme probably needs to be fixed), and set up
what I think are some good defaults.  If you don't like them (which most
of you Europeans probably won't), go into the mythweb settings and
change dates to your hearts' content.  Since sessions should be stored
indefinitely, you shouldn't really ever need to re-change them, except
of course when you connect from a different machine.

Also, if you're using .12 and not cvs, you'll need to change the 26 on
line 118 of includes/mythbackend.php to a 22.

-Chris