Added externs declarations to header files to handle C++ compilation.

Cleaned up BACnet/IP API a little.

bacnet-stack/bigend.h

@@ -1,6 +1,10 @@
 #ifndef BIGEND_H
 #define BIGEND_H
 
+#ifdef __cplusplus
+extern "C" {
+#endif /* __cplusplus */
+
 // Big-Endian systems save the most significant byte first. 
 // Sun and Motorola processors, IBM-370s and PDP-10s are big-endian.
 // for example, a 4 byte integer 67305985 is 0x04030201 in hexidecimal.
@@ -19,4 +23,8 @@
 
 int big_endian(void);
 
+#ifdef __cplusplus
+}
+#endif /* __cplusplus */
+
 #endif