Dropping xfce-utils for 4.10

[Nick Schermer]

FYI,

Today I've merged the appfinder branch in to master. It's not finished
yet, but already as functional as the old appfinder + xfrun4.

With this merge, it is also the start of dropping xfce-utils
(https://wiki.xfce.org/releng/4.10/roadmap/xfce-utils) and move the
useful parts of this module into other modules.
For that I've created branches in libxfce4ui and xfce4-session. What
remains is moving some scripts into xfce4-docs.

When the help things are also moved, I'll merge the various branches
in master, but this will lead into various package conflicts. To avoid
this, you should drop xfce-utils first and then update xfce4-session
and libxfce4ui.

Nick