refactored muPDF integration to use strictly the fitz.h API
refactored muPDF integration to use strictly the fitz.h API

This will allow for reading XPS and CBZ documents, since those are
supported by muPDF (not tested yet)

frankyifei/koreader-base,mwoz123/koreader,ashhher3/koreader,Hzj-jie/koreader-base,houqp/koreader-base,NiLuJe/koreader-base,NickSavage/koreader,frankyifei/koreader-base,houqp/koreader,Hzj-jie/koreader-base,apletnev/koreader,NiLuJe/koreader-base,robert00s/koreader,NiLuJe/koreader-base,chrox/koreader,NiLuJe/koreader-base,Frenzie/koreader-base,NiLuJe/koreader,mihailim/koreader,Hzj-jie/koreader,apletnev/koreader-base,houqp/koreader-base,NiLuJe/koreader,apletnev/koreader-base,apletnev/koreader-base,houqp/koreader-base,poire-z/koreader,koreader/koreader-base,lgeek/koreader,chihyang/koreader,Hzj-jie/koreader-base,koreader/koreader-base,poire-z/koreader,Hzj-jie/koreader-base,ashang/koreader,Frenzie/koreader-base,koreader/koreader-base,koreader/koreader-base,Markismus/koreader,Frenzie/koreader,houqp/koreader-base,frankyifei/koreader-base,pazos/koreader,Frenzie/koreader,Frenzie/koreader-base,koreader/koreader,apletnev/koreader-base,frankyifei/koreader-base,noname007/koreader,koreader/koreader,frankyifei/koreader,Frenzie/koreader-base