clients/editor.c: Ignore ESC key

Otherwise, editor would print the "unknown UTF-8 glyph" boxes.

clients/editor.c

@@ -1155,6 +1155,8 @@ key_handler(struct window *window,
 				widget_schedule_redraw(entry->widget);
 			}
 			break;
+		case XKB_KEY_Escape:
+			break;
 		default:
 			if (xkb_keysym_to_utf8(sym, text, sizeof(text)) <= 0)
 				break;