Update block_data.py

[JonShort4]

Was getting 2CHN instead of final absorbance (AB), so with some trial and error to the block_data I got absorbance for three different instruments.

[Late515G]

Thanks for this work. Could you please explain the conditions that guarantee correct absorbance values, even when using different instruments. ? Why must self.channel_type be equal to 16, and what does the value 1332 represent for self.chunk_size ?

[JonShort4]

I wish I knew! I've not found any documentation for this code that explains. These were the conditions that gave the same absorbance results as values exported from Opus. I cannot guarantee that it will work for all instruments and settings, but it is what worked for us.