Turn into autonomous module by referencing local copy of grid.h

cgridinterface.c

@@ -1,8 +1,6 @@
 #include <assert.h>
 #include <stdlib.h>
 
-#include <grid.h>
-
 #include "geometry.h"
 #include "cgridinterface.h"
 

cgridinterface.h

@@ -19,8 +19,7 @@
 #ifndef CGRIDINTERFACE_H
 #define CGRIDINTERFACE_H
 
-#include <grid.h>
-
+#include "grid.h"
 #include "preprocess.h"
 
 #ifdef __cplusplus