Several minor improvements of evernote plugin (#2573)
Several minor improvements of evernote plugin (#2573)

* Several minor improvements of evernote plugin
NiLuJe/koreader,lgeek/koreader,Frenzie/koreader,Markismus/koreader,robert00s/koreader,mwoz123/koreader,apletnev/koreader,houqp/koreader,poire-z/koreader,koreader/koreader,poire-z/koreader,Frenzie/koreader,pazos/koreader,koreader/koreader,NiLuJe/koreader,mihailim/koreader,Hzj-jie/koreader