GetEntries sets up a list of channels that get one line at a time from each file down each channel.

GetSampledEntries wraps GetEntries and returns a list of channels that provide sampled entries.

foo.log gets rotated to foo.log.1, new entries go to foo.log.

foo.log.OLDSTAMP gets closed, new entries go to foo.log.NEWSTAMP NOT YET IMPLEMENTED.

State is what's stored in a statefile.