unistd.h needed for usleep(3)

--- Ui.cpp.orig	Sun Aug 30 09:04:24 2015
+++ Ui.cpp	Fri May 27 00:19:26 2016
@@ -24,6 +24,7 @@
 
 #include <cstdio>
 #include <cstdlib>
+#include <unistd.h>
 #include <boost/format.hpp>
 #include <boost/foreach.hpp>
 #include <boost/algorithm/string.hpp>
