fix bug in TOC construction in cre.cpp
fix bug in TOC construction in cre.cpp

first toc entry should start with index 1 instead of 0

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