[Koha] Importing encrypted patron passwords

[Mark Alexander]

I've managed to get the database upgrade to succeed, but it failed at four different
places:

* 3.19.00.037
* 3.21.00.027
* 3.23.00.041
* 16.06.00.050

The fixes involved manual updates to the database, or commenting out lines
in updatedatabase.pl, or both.

Thanks to all those who offered help.

-- 
By doing just a little every day, I can gradually let
the task completely overwhelm me. --Ashleigh Brilliant