Fix triangle.h conflict with OpenFOAM

- Rename triangle.h to cork_triangle.h to avoid conflict with OpenFOAM's triangle.H
- Add header guards (#ifndef CORK_TRIANGLE_H) to prevent multiple inclusion
- Add REAL type definition to prevent compilation errors
- Update all references from triangle.h to cork_triangle.h in:
  - src/isct/triangle.c
  - src/mesh/mesh.isct.tpp

This resolves the triangulateio struct redefinition error when building
with OpenFOAM integration.

src/isct/cork_triangle.h

@@ -1,3 +1,14 @@
+#ifndef CORK_TRIANGLE_H
+#define CORK_TRIANGLE_H
+
+/* Define REAL type */
+#ifndef SINGLE
+#define REAL double
+#else
+#define REAL float
+#endif
+
+
 /*****************************************************************************/
 /*                                                                           */
 /*  (triangle.h)                                                             */
@@ -287,3 +298,4 @@ void trifree(void *memptr);
 /*void triangulate();
 void trifree();*/
 /*#endif*/ /* not ANSI_DECLARATORS */
+#endif /* CORK_TRIANGLE_H */

src/isct/triangle.c

@@ -354,7 +354,7 @@
 #include <fpu_control.h>
 #endif /* LINUX */
 #ifdef TRILIBRARY
-#include "triangle.h"
+#include "cork_triangle.h"
 #endif /* TRILIBRARY */
 
 /* A few forward declarations.                                               */

src/mesh/mesh.isct.tpp

@@ -35,7 +35,7 @@
 
 #define REAL double
 extern "C" {
-#include "triangle.h"
+#include "cork_triangle.h"
 }
 
 struct GenericVertType;