Engine-Tests: fixed Db4oMessageBufferTests.Reopen() test-case
Engine-Tests: fixed SqliteMessageBufferTests.Reopen() test-case
Engine-Tests: offset is less confusing than index
Engine: enabled WAL in SqliteMessageBuffer to fix awful performance
Engine: dispose all Command instances in SqliteMessageBuffer
Engine: no need to select the ID column in SqliteMessageBuffer.GetRange()
Engine: implemented SqliteMessageBuffer.RemoveAt()
Engine: implemented SqliteMessageBuffer.Dispose()
Engine: implemented SqliteMessageBuffer.GetEnumerator()
Engine: provide enumerator based MessageBufferBase.CopyTo() as default implementation
Engine-Tests: fixed Db4o/SqliteMessageBufferTests.ImplicitRemoveAt() test-case
Engine-Tests: removed useless SqliteMessageBufferTests.ImplicitFlush() test-case
Engine: implemented truncation of SqliteMessageBuffer