SortWidget: Add support for checkmarks
SortWidget: Add support for checkmarks

Hzj-jie/koreader,Markismus/koreader,NiLuJe/koreader,poire-z/koreader,Frenzie/koreader,NiLuJe/koreader,poire-z/koreader,koreader/koreader,koreader/koreader,mwoz123/koreader,Frenzie/koreader,pazos/koreader