Moved BBS startup ptr from scfg_t to sbbs_t.

src/sbbs3/answer.cpp

src/sbbs3/chat.cpp

src/sbbs3/execfunc.cpp

src/sbbs3/execnet.cpp

src/sbbs3/logon.cpp

src/sbbs3/main.cpp

src/sbbs3/scfgdefs.h

src/sbbs3/telgate.cpp

src/sbbs3/useredit.cpp

src/sbbs3/xtrn.cpp