$PnE based rescaling is not heeded

[xiamaz]

According to the FCS 3.1 specification (and probably older ones, too), logarithmic data channels can be saved in linearized form with $PnE specifying the logarithmic range and minimal value.

Currently the library does not transform these values into logarithmic form for later transformations.

[eyurtsev]

Feel free to file a PR if you know how to fix this

My only concern would be to provide the user with enough information to know that a transformation has been applied to the data

[bpteague]

Hi @xiamaz - for what it's worth, I've just implemented this functionality in my project, cytoflow, which builds on fcsparser. It's a pretty straightforward transformation to do once you've sucked the data in with fcsparser -- see commit cytoflow/cytoflow@039f9ab for details.