* Object level restrictions in outliner

This adds the ability to restrict an individual object from:
- being visible in the 3D View
- being selectable in the 3D View
- being renderable
with 3 columns of buttons in the outliner.

These restrictions are further down the hierarchy than layers, so for example if an object is in an invisible layer, it will be invisible regardless of whether the object's own visibility setting is on or off. This works on a different conceptual level than layers, being better for more quick interaction (like temporarily making a mesh unselectable while you're posing its armature), rather than so much for scene organisation.

The 3 columns of icons can be turned off in the Outliner View menu.

Along with this is some small cleaning up in interface_icons.c and outliner.c.

source/blender/src/drawobject.c

@@ -3823,6 +3823,8 @@ void draw_object(Base *base, int flag)
 
 	ob= base->object;
 
+	if (ob->restrictflag & OB_RESTRICT_VIEW) return;
+
 	/* xray delay? */
 	if((flag & DRAW_PICKING)==0 && (base->flag & OB_FROMDUPLI)==0) {
 		/* xray and transp are set when it is drawing the 2nd/3rd pass */