* nsterm.h (EmacsPrefsController.cursorBlinkSlider): Only define

* nsterm.h (EmacsPrefsController.cursorBlinkSlider): Only define
	under GNUstep.
	(ns_query_color): New declaration.

	* nsterm.m (ns_confirm_quit): New variable.
	(ns_set_default_prefs, syms_of_nsterm, ns_term_init): Initialize it.
	(EmacsApp-applicationShouldTerminate:): Use it.
	(EmacsPrefsController): Let user set it.
	(ns_query_color): New function.
	(ns_defined_color): Use it.
	(ns_initialize): Drop.
	(ns_term_init): Add two lines from ns_initialize(), and set
	input_interrupt_mode to nil.

	* image.c (svg_load_image): Don't right-shift background RGB when
	obtained from FRAME_BACKGROUND_PIXEL. Under HAVE_NS use ns_query_color.