Implement the "scan_stream" method that can read tags from any
input_stream object.  This requires a FLAC__IOCallbacks implementation
based on the input_stream API.

g_file_error_quark() is meant to be used with the GFileError enum
which does not correspond with errno, but must be converted with
g_file_error_from_errno().

At the same time, this removes g_strerror() use for
g_file_error_quark().

Improved support for scanning http:// resources.

Merge common code.

Use the new FLACMetadataIterator C++ class, which is more powerful.

Not using libFLAC++ because this library adds a lot of overhead due to
virtual method calls.  This new class library is zero-overhead.

This has been deprecated by the "embcue" playlist plugin.

The "opusinfo" program complained about preskip value that was too
small.  This commit uses OPUS_GET_LOOKAHEAD to obtain the number of
frames that shall be silence at the beginning.

Improves quality by not squeezing 32 bit samples down to 16 bit, and
then back to 32 bit floating point.  Reduces CPU usage by skipping a
conversion step.

If there are multiple pages, the last partial page must be flushed.

Eliminate the evil goto.

This is necessary for Ogg packets that span more than one page.

We can only check for negative values if the variable is signed.

Make sure the file header gets written at the beginning, before
_write() gets called.

Move the raw buffer to struct shout_data.

Make it a local variable instead.