modules/gui/beos/PreferenceWindow.h/.cpp

	- added settings for screenshot path and image format

	- removed "Save" button, added "Cancel" and "Revert" buttons

	- added revert functionality

	- changed class design for cleaner functionality,
		separated ApplyChanges() into more functions
		to have finer control

	- added more error checking and fixed memory leaks
		(config_GetPsz() returns char*, not const char*!)

	- all settings are now correctly saved and restored

	- some more cosmetic changes


modules/gui/beos/InterfaceWindow.h/.cpp

	- updated vlc way of saving settings to be on par with BeOS way
		and made it selectable in the code which way is used.
		However, the VideoSettings are still only savable in
		the BeOS way.

	- if dvd menus are used, the navigation menu enables a
		"Goto Menu" item. Unfortunately, I don't see a clean
		way to really detect the usage of dvd/dvdold in the
		currently playing stream. I wouldn't want to see
		if a playlist item has "dvd:" or "dvdold:" prepended
		at each interface update.