opusfile version 0.3

The opusfile and opusurl libraries provide a high-level API for
decoding and seeking within .opus files on disk and over http.

It depends on libopus, libogg, and openssl.

Changes since the previous release:

- Fix a buffer overflow downmixing multichannel files.
- UTF-8 filename support on Windows.
- HTTP(S) url support on Windows.
- Support Windows system certificate store for HTTPS.
- New project files for MS Visual Studio.
- New gain control API with op_set_gain_offset() and op_get_track_gain().
- Documentation and build improvements.
- HTTP(S) support split into a separate opusurl library.
- Implement soft-clip for paths where libopus doesn't.
- opusfile_example now outputs WAV.
- Fix http basic auth.
- Fix 255 packet-per-page assert.

The library is functional, but there are likely issues
we didn't find in our own testing. Please give feedback
in #opus on irc.freenode.net or at opus@xiph.org.
This tag has no release notes.