Refactor definitions of items, item and field. Add examples
Refactor definitions of items, item and field. Add examples

SouthStar/portia,CENDARI/portia,PrasannaVenkadesh/portia,Youwotma/portia,flip111/portia,pombredanne/portia,NoisyText/portia,amikey/portia,chennqqi/portia,hanicker/portia,Suninus/portia,amikey/portia,hanicker/portia,anjuncc/portia,CENDARI/portia,SouthStar/portia,CENDARI/portia,nju520/portia,flip111/portia,anjuncc/portia,NicoloPernigo/portia,verylasttry/portia,hanicker/portia,Youwotma/portia,verylasttry/portia,NicoloPernigo/portia,nju520/portia,hmilywb/portia,anjuncc/portia,amikey/portia,PrasannaVenkadesh/portia,sntran/portia,SouthStar/portia,PrasannaVenkadesh/portia,livepy/portia,chennqqi/portia,verylasttry/portia,PrasannaVenkadesh/portia,lodow/portia-proxy,Suninus/portia,verylasttry/portia,amikey/portia,NoisyText/portia,asa1253/portia,sntran/portia,livepy/portia,livepy/portia,Suninus/portia,naveenvprakash/portia,chennqqi/portia,naveenvprakash/portia,sntran/portia,Youwotma/portia,CENDARI/portia,NoisyText/portia,anjuncc/portia,NicoloPernigo/portia,asa1253/portia,livepy/portia,pombredanne/portia,Suninus/portia,naveenvprakash/portia,asa1253/portia,hmilywb/portia,sntran/portia,NoisyText/portia,Youwotma/portia,flip111/portia,asa1253/portia,lodow/portia-proxy,nju520/portia,NicoloPernigo/portia,pombredanne/portia,SouthStar/portia,hmilywb/portia,nju520/portia,lodow/portia-proxy,hanicker/portia,chennqqi/portia,pombredanne/portia,naveenvprakash/portia,hmilywb/portia,flip111/portia