Non-POSIX compliant test used in startxfce4 (Bug 10828)

Patch and bug report by seejay
The command line arguments "--help" and "--with-ck-launch"
can't be used on systems which have a non-bash /bin/sh
(e.g. Debian, as far as I'm aware). This is due to the use
of "=="  instead of "=" in test commands, which is a bash
extension.
Handle gpg and ssh agents separately.

This allows start gpg and ssh agents separately from
each other.
Update xflock4 (Bug 10217)

Complete rewrite of xflock4 that aims to be more reliable and
support more screen savers and lockers.