binding: supply the keycode for most special keys directly

Instead of figuring them out from the string.  This is possible
because those dedicated editing keys cannot be rebound anyway.

src/proto.h

@@ -368,7 +368,7 @@ size_t length_of_list(int menu);
 const sc *first_sc_for(int menu, void (*func)(void));
 int sc_seq_or(void (*func)(void), int defaultval);
 functionptrtype func_from_key(int *kbinput);
-void assign_keyinfo(sc *s, const char *keystring);
+void assign_keyinfo(sc *s, const char *keystring, const int keycode);
 void print_sclist(void);
 void shortcut_init(void);
 #ifndef DISABLE_COLOR

src/rcfile.c

@@ -478,7 +478,7 @@ void parse_binding(char *ptr, bool dobind)
 	}
 
 	newsc->menus = menu;
-	assign_keyinfo(newsc, keycopy);
+	assign_keyinfo(newsc, keycopy, 0);
 
 	/* Do not allow rebinding a frequent escape-sequence starter: Esc [. */
 	if (newsc->meta && newsc->keycode == 91) {