Split onground/onroof into visual and logical variables

I will need to separate these into two different variables because I
will need to move logical onground/onroof assignments to the start of
gamelogic() - if I kept them together, however, that would change the
visuals of onground/onroof, which I want to keep consistent with 2.2.

desktop_version/src/Ent.cpp

@@ -46,6 +46,8 @@ void entclass::clear(void)
 	gravity = false;
 	onground = 0;
 	onroof = 0;
+	visualonground = 0;
+	visualonroof = 0;
 
 	onentity = 0;
 	harmful = false;