layers: Fix the layer toggle behaviour

When toggling a layer, the same keycode should toggle the layer off, too.
Without this, toggling layers won't work at all, because the target layer will
never be turned off.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>

src/layers.cpp

@@ -29,6 +29,9 @@ static void handle_keymap_key_event(Key keymapEntry, uint8_t keyState) {
 
         // switch keymap and stay there
     } else if (key_toggled_on(keyState)) {
+        if (Layer.isOn (keymapEntry.keyCode) && keymapEntry.keyCode)
+            Layer.off(keymapEntry.keyCode);
+        else
             Layer.on(keymapEntry.keyCode);
     }
 }