refactor out Docview:render calling into a seperate function so that it won't be called when redering is not neccessary.
refactor out Docview:render calling into a seperate function
so that it won't be called when redering is not neccessary.

Frenzie/koreader-base,koreader/koreader-base,apletnev/koreader-base,Hzj-jie/koreader-base,apletnev/koreader-base,houqp/koreader-base,Frenzie/koreader-base,apletnev/koreader-base,Hzj-jie/koreader-base,frankyifei/koreader-base,NiLuJe/koreader-base,NiLuJe/koreader-base,houqp/koreader-base,NiLuJe/koreader-base,houqp/koreader-base,Frenzie/koreader-base,frankyifei/koreader-base,koreader/koreader-base,frankyifei/koreader-base,frankyifei/koreader-base,NiLuJe/koreader-base,koreader/koreader-base,Frenzie/koreader-base,Hzj-jie/koreader-base,apletnev/koreader-base,houqp/koreader-base,koreader/koreader-base,Hzj-jie/koreader-base