all (or most, there are limits still) of the maps on a server with many
maps.
move the optional progs funcs into sv_funcs_t and add UserInfoChanged,
ChatMessage and LocalinfoChanged callback support.
clean up PF_setinfo (and SV_SetInfo_f and SV_Localinfo_f) using shared code
where possible und to use the UserInfoChanged and LocalinfoChanged
callbacks.
add chat message callback to SV_Say. if it returns zero, normal chat
handling is done, otherwise it's assumed to have been handled by the progs.
provide a hook for unkown user commands. non-zero return means it's been
handled.
