Support separate files per recording option in NeuralynxRawIO

[alafuzof]

Hi,

Since version 5.7.0 Neuralynx Cheetah has supported an option for creating "separate files per recording". When stopping and restarting a recording within the same acquisition with this option enabled, Cheetah creates multiple files for each acquisition entity as well as for events. Thus, you get a folder like the following, where CSC.ncs corresponds to the first recording and so on:

CSC.ncs
CSC_0001.ncs
CSC_0002.ncs
Events.nev
Events_0001.nev
Events_0002.nev

Currently NeuralynxRawIO reads directories like this as containing multiple signal channels for the same acquisition entity (e.g. signal_channels: [CSC, CSC, CSC] in the example above). Ideally, I would like to have separate segments for each set of files. Nota bene: as far as I know there's nothing that rules out discontinuities within a given .ncs file (e.g. if the recording system experiences a hiccup) - so proper handling of these directories requires handling both the separate files and any discontinuities within them.

I would be happy to work on adding support for these recordings, but I would like to hear your suggestions with regards to how to integrate the file handling to the existing code base. @samuelgarcia @JuliaSprenger any comments?