Add limits.h to allow for illumos to compile.

Closes #331

src/frontend/terminaloverlay.h

@@ -39,6 +39,7 @@
 #include "parser.h"
 
 #include <vector>
+#include <limits.h>
 
 namespace Overlay {
   using namespace Terminal;

src/network/transportsender.cc

@@ -39,6 +39,8 @@
 #include "transportsender.h"
 #include "transportfragment.h"
 
+#include <limits.h>
+
 using namespace Network;
 using namespace std;
 

src/statesync/completeterminal.cc

@@ -35,6 +35,8 @@
 
 #include "hostinput.pb.h"
 
+#include <limits.h>
+
 using namespace std;
 using namespace Parser;
 using namespace Terminal;