Implemented FormID counter.

espReader/ESPReader.h

@@ -272,6 +272,11 @@ extern "C" {
 	 */
 	size_t espr_decompressed_size(char *data, size_t size);
 
+	/* Counts the number of formids present in the esp/esm data. This should be
+	 * equal to the number of records.
+	 */
+	size_t espr_formid_count(char *data, size_t size);
+
 // End C++ guard
 #ifdef __cplusplus
 }