Beginning of experimental support for a smarter showmissing

Smarter showmissing by storing the next episode date.  Also this allows
sorting of shows by next date in calendar
Add name to 'sort by' when sorting by date
Add debugging options to transmission_done.bash

If a copy to destination dir didn't work properly the changes now will
make it easier to find out why.

Each time the bash file is called by transmission, in addition to the
usual info written to the log file, a debug command is written as well.
If that command is copied and then used on the command line, it can be
used to debug what the problem was.
Cherry pick from smarter_showmissing branch
Merge branch 'smarter_showmissing'