This function gets a datablk from the entropy coder. The sample sin the block, which consists of the quantized coefficients from the quantizer, are scaled by the values given for any ROIs specified.
The function calls on a ROIMaskGenerator to get the mask for scaling the coefficients in the current block.
The data returned by this method is a copy of the orignal data. Therfore it can be modified "in place" without any problems after being returned. The 'offset' of the returned data is 0, and the 'scanw' is the same as the code-block width. See the 'CBlkWTData' class.
