dbus-launch in MacOSX build

[Geert Janssens]

The MacOSX gnucash-setup-env script calls dbus-launch when no dbus session is 
found. This has been there since the script was first checked in in svn.

According to the dbus-launch man page, a process that tries to use dbus when 
there's no dbus session will call dbus-launch automatically. So what is the 
motivation for this explicit call ?

I'm asking because I'm in the process of eliminating the startup scripts (in 
favour of directly starting from the gnucash binary). I can have the binary 
set up the environment properly, but the dbus-launch execution kind of 
requires to keep the startup script on MacOS.

Geert