better command output redirection handling: maplist over rcon should show

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.

qw/include/sv_demo.h

@@ -102,6 +102,7 @@ typedef struct {
 	byte       *mfile;
 	byte        buffer[20 * MAX_MSGLEN];
 	int         bufsize;
+	int         forceFrame;
 } demo_t;
 
 extern demo_t      demo;