[fix] GestureDetector: multiswipe rotation (#4613)
[fix] GestureDetector: multiswipe rotation (#4613)

Reported by @poire-z in <https://github.com/koreader/koreader/pull/4607#issuecomment-464622906>.

Also refactor slightly along the way to make the translations more straightforward.
mihailim/koreader,mwoz123/koreader,NiLuJe/koreader,poire-z/koreader,Frenzie/koreader,poire-z/koreader,koreader/koreader,Hzj-jie/koreader,pazos/koreader,koreader/koreader,houqp/koreader,Markismus/koreader,NiLuJe/koreader,Frenzie/koreader