Log Message:
Update to 0.1.8

* opusenc required audio/flac

Changelog:
opus-tools 0.1.8
This release fixes a memory corruption bug with FLAC album art
handling.

opus-tools 0.1.7
This release has numerious build fixes, including updated Visual
Studio project files to match similar changes in the opus package.
Support encoding from FLAC files. Metadata tag support, including
album art. Use the new surround encoder API in opus 1.0.3. The
opusenc --uncoupled switch no longer works.