Initial support for polls.

src/sbbs3/atcodes.cpp

src/sbbs3/getmsg.cpp

src/sbbs3/js_msgbase.c

src/sbbs3/readmsgs.cpp

src/sbbs3/sbbsdefs.h

src/smblib/smbadd.c

src/smblib/smbdefs.h

src/smblib/smblib.h