Add support for CSV log reader to handle multiple channels

### Is your feature request related to a problem? Please describe.
Right now the `CSVReader` and `CSVWriter` classes do not support files with multiple channels. It would be great to add that functionality.

### Describe the solution you'd like
CSV IO library supports multiple channels, like ASC IO library.

### Describe alternatives you've considered
Creating multiple log files for each channel is tedious and clumsy.