plugins/NewsDownloader: add never download images (#6003)
plugins/NewsDownloader: add never download images (#6003)

Closes #5924.
mwoz123/koreader,Markismus/koreader,koreader/koreader,NiLuJe/koreader,poire-z/koreader,Frenzie/koreader,NiLuJe/koreader,mihailim/koreader,Hzj-jie/koreader,koreader/koreader,Frenzie/koreader,poire-z/koreader,pazos/koreader