New @-codes: GETKEY and WAIT:<milliseconds>

GETKEY waits indefinitely for any key press by the user (resolves issue #245).
WAIT:<n> waits for up to n-milliseconds for a key press and then continues on.

For both cases, the key pressed is not echoed or acted upon in any way. Ctrl-keys could be handled by global or built-in ctrl-key handlers, so those would be the exception.

src/sbbs3/atcodes.cpp

@@ -699,6 +699,16 @@ const char* sbbs_t::atcode(char* sp, char* str, size_t maxlen, long* pmode, bool
 		return(nulstr);
 	}
 
+	if(strcmp(sp, "GETKEY") == 0) {
+		getkey();
+		return(nulstr);
+	}
+
+	if(strncmp(sp, "WAIT:", 5) == 0) {
+		inkey(K_NONE, atoi(sp + 5));
+		return(nulstr);
+	}
+
 	if(!strcmp(sp,"PAUSE") || !strcmp(sp,"MORE")) {
 		pause();
 		return(nulstr);