exit from filechooser on BACK and HOME
exit from filechooser on BACK and HOME

This makes it easy to exit completly from document with HOME+HOME
which is much easier and intuitive than HOME+BACK

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