itip-formatter.c: the whole logic for "reply to organize" was
improved.
If an organizer exists, replying is enabled. Sending a reply is
enabled by default if the event looks like a meeting (= has
attendees). The wish of the organizer to not get replies is
checked (previous Evolution releases ignored it); in this case the
default is to not send a reply. In all cases the user can override
the default.
Merged from 2.24 branch.
svn path=/trunk/; revision=36594
6c06b962eb