duplicates handling for forceRecord and changeRecord methods, tests and docs

src/base.h

@@ -47,6 +47,7 @@ template <class K, class V>
 class Cache;
 
 typedef MDB_txn* TransactionID;                         /**<I'm going to use transaction pointers as transaction IDs*/
+typedef uint32_t SizeType;                              /**<All LMDBAL sizes are uint32_t*/
 
 class Base {
     friend class iStorage;