Added Cut Item (Ctrl-X) support.

src/sbbs3/scfg/scfg.c

src/sbbs3/scfg/scfgchat.c

src/sbbs3/scfg/scfgmsg.c

src/sbbs3/scfg/scfgxfr1.c

src/sbbs3/scfg/scfgxfr2.c

src/sbbs3/scfg/scfgxtrn.c