These may be redefined to customize log rotation path prefixes,
including use of a directory. File extensions are still up to
individual log writers to add themselves during the actual rotation.
These new also allow for some simplication to the default
ASCII postprocessor function: it eliminates the need for it doing an
extra/awkward rename() operation that only changes the timestamp format.
This also teaches the supervisor framework to use these new options
to rotate ascii logs into a log-queue/ directory with a specific
file name format (intended for an external archiver process to
monitor separately).
