Add 14th bit to XK_SWITCH_MOD bitmask
The bits of uint signal in an XKeyEvent which concern the key group (keyboard
layout) are bits 13 and 14, as documented here:
In the older version, only bit 13 was marked as part of XK_SWITCH_MOD, this
causes issues for users who have more than two keymaps. the 14th bit is not
in ignoremod, key sequences are not caught by match(), if they switch to a third
or fourth keyboard.