Allow GUIs to actually parse command line arguments again.

GUIs can now parse command line arguments that start with an option starting with '-' again.
They can handle any number of arguments after that.
GUIs can now print their own specific help.
Win32Gui and QtGui not tested. (I'll see if I can update QtGui for Qt 4 or 5, if there is interest)

Previously the command line parsing code aborted on any option starting with '-', now it can ask the GUI to handle that option (and further parameters).

(Written as a upgrade to 4.3 (from 3.x) broke our command line parameters and I started to fix that bug as a part of it (See http://trac.wildfiregames.com/ticket/2488 ))