Put version information in the header

This is important so that it is always known which version of the
library is used, especially if the C and Header files have just been
copy pasted to another code base.

cJSON.h

@@ -28,6 +28,10 @@ extern "C"
 {
 #endif
 
+/* project version */
+#define CJSON_VERSION_MAJOR 1
+#define CJSON_VERSION_MINOR 2
+#define CJSON_VERSION_PATCH 0
 #include <stddef.h>
 
 /* cJSON Types: */