DMSO Cal. adjustment for c(t)

[cvallee]

At the moment, the concentration function c(t) is generated using the signal of the FC1 channel from the DMSO Cal. cycle only.

Desired behaviour:
For a given Sample cycle:

• Check the active channel used to get the signal (i.e. FC2, FC3 or FC4)
• Get the closest DMSO Cal. cycle prior to Sample cycle (and make sure is valid, see Add QC for Blank and DMSO Cal. cycles #4)
• Make sure channel of DMSO Cal. cycle matches the active channel of the Sample cycle
• Get the closest Blank cycle prior to Sample cycle (and make sure is valid, see Add QC for Blank and DMSO Cal. cycles #4)
• Make sure channel of Blank cycle matches the active channel of the Sample cycle
• Subtract Blank 'active channel' signal from DMSO Cal. 'active channel' signal
• Use subtracted signal to generate the concentration function c(t)