TouchMenu: don't allow swipe south to close menu
TouchMenu: don't allow swipe south to close menu

This is mostly needed because opening the menu with swipe
is actually done by handling a pan south event, and so the
final swipe event is another event, that is then handled
by TouchMenu, which would straight away close itself.

NiLuJe/koreader,poire-z/koreader,Frenzie/koreader,koreader/koreader,koreader/koreader,poire-z/koreader,NiLuJe/koreader,Frenzie/koreader