Add couple of missing header files needed by GCC 4.7.

src/cat/LuaScriptInterface.cpp

@@ -11,6 +11,7 @@
 #include <algorithm>
 #include <locale>
 #include <fstream>
+#include <unistd.h>
 #include "Config.h"
 #include "Format.h"
 #include "LuaLuna.h"

src/simulation/StructProperty.h

@@ -10,6 +10,7 @@
 #define The_Powder_Toy_StructProperty_h
 
 #include <string>
+#include <stdint.h>
 
 struct StructProperty
 {