Opus support, ogg enhancements

3.1.0 adds support for the Opus output type, and cleans up some man/documentation/comment language. Also adds support for ogg quality level -1, and fractional ogg quality levels.

3.0.0

First 3.x release, fully refactored, brought up to date, modernized Perl 5. Using explicit minimum Perl version 5.010, warnings, strict mode. Adds --test flag, --clean directory cleanup, fixes mp3 tagging bugs, cleans up output, adds man page.