The Dicom codec returns black images when highbit=31

[Paolo Brandoli]

The Dicom codec returns black images when highbit=31 This is caused by this line: imbxUint32 mask=(imbxUint32)0x1<<(highBit+1);

The result of the shift is undefined when highbit=31 (shift of 32 bits).

[Paolo Brandoli]

- Fixes #74 (When the transfer syntax as implicit VRs then the VR for image data should be OW) - Fixes #73 (The Dicom codec returns black images when highbit=31) - Fixes #75 (The dataset doesn't set the b2complement flag when the data is stored in signed 32bit)

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