PolyFile v0.4.2

Updates to the command line interface to allow for greater flexibility in specifying output formats and output files. These updates are backwards-compatible, however, in the forthcoming v0.5.* release there will be a breaking change in the output: PolyFile will then default to the mime output format (to mimic the behavior of the file command) rather than the current sbud output.

This release also includes optimizations to the libmagic search and string tests which should result in significant speed improvements.