made wren version number accessable via function (#958)

src/include/wren.h

@@ -296,6 +296,11 @@ typedef enum
   WREN_TYPE_UNKNOWN
 } WrenType;
 
+// Get the current wren version number.
+//
+// Can be used to range checks over versions.
+WREN_API int wrenGetVersionNumber();
+
 // Initializes [configuration] with all of its default values.
 //
 // Call this before setting the particular fields you care about.

src/vm/wren_vm.c

@@ -36,6 +36,11 @@ static void* defaultReallocate(void* ptr, size_t newSize, void* _)
   return realloc(ptr, newSize);
 }
 
+int wrenGetVersionNumber() 
+{ 
+  return WREN_VERSION_NUMBER;
+}
+
 void wrenInitConfiguration(WrenConfiguration* config)
 {
   config->reallocateFn = defaultReallocate;