Support for Windows (Visual C)

context.cpp

+#ifdef _WIN32
+#include <io.h>
+#include <direct.h>
+#define getcwd _getcwd
+#else
+#include <unistd.h>
+#endif
+
 #include <cstring>
 #include <iostream>
 #include <sstream>
-#include <unistd.h>
 #include "context.hpp"
 #include "constants.hpp"
 #include "color_names.hpp"

document.cpp

+#ifdef _WIN32
+#define S_ISDIR(mode) (((mode) & S_IFMT) == S_IFDIR)
+#endif
+
 #include <cstdio>
 #include <cstring>
 #include "document.hpp"

sass_interface.cpp

+#ifdef _WIN32
+#include <io.h>
+#else
+#include <unistd.h>
+#endif
+
 #include <iostream>
 #include <sstream>
 #include <string>
 #include <cstdlib>
-#include <unistd.h>
 #include <iostream>
 #include "document.hpp"
 #include "eval_apply.hpp"