add visual indication on document loading This should implement #265.
add visual indication on document loading
This should implement #265.

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