change session id creation from & time to ^ to get one without a username

src/session.c

@@ -22,7 +22,7 @@ sessionCtor(void * _this, va_list * params)
 	size_t nuname = va_arg(* params, size_t);
 
 	this->livetime = time(NULL) + SESSION_LIVETIME;
-	this->id       = sdbm((unsigned char *)uname, nuname) & this->livetime;
+	this->id       = sdbm((unsigned char *)uname, nuname) ^ this->livetime;
 
 	this->username = malloc(nuname + 1);
 	this->username[nuname] = 0;