DmoMp3Decoder incorrectly Dispose the stream

[fabri9532]

If I create a DmoMp3Decoder with a filename it is correct for DmoMp3Decoder to dispose the stream because it is opened by DmoMp3Decoder.

If I create a DmoMp3Decoder passing a stream as constructor argument, DmoMp3Decoder should not dispose the stream as it was created externally.
Instead in CSCore v1.2.1.2 DmoMp3Decoder dispose the stream even if passed as an argument to the constructor.