HashTrieCompactingTest: number of steps was increased to 5000, exceptions from compaction thread are now treated as errors, entrySet and keySet checks are performed iff no compaction is in progress (size check is always performed)
HashTrieEngine:
  modificationsDuringCompaction map was introduced. It's modified in put() and remove() and read in get()
  isCompactionInProgress() function was added
  compactionInProgress check was added to clear()
ShardingNode: checks for compactionInProgress and corresponding 'no' reponses were added
README.md: some information about compacting algo was added