xgb: fix spurious key up/down events

The KeymapNotify event handling code wasn't correctly translating
X keysym to wde key string. This could result in spurious events
for keys where the two are different (eg. left shift is "Shift_L"
in X11 and "left_shift" in wde).

xgb/events.go

@@ -159,7 +159,7 @@ func (w *Window) handleEvents() {
 				for j := 0; j < 8; j++ {
 					if mask & (1 << uint(j)) != 0 {
 						keycode := xproto.Keycode(8 * (i + 1) + j)
-						key := keybind.LookupString(w.xu, 0, keycode)
+						key := keyForCode(keybind.LookupString(w.xu, 0, keycode))
 						newDownKeys[key] = true
 					}
 				}