Preparing to move logger calls out of lower-level libaries, and
propagating error details to the caller instead.

And specify whether generic tags are being scanned.

This code has been moved to LoadFromArchive().

Load APE/ID3 tags from archives.

This commit adds support for APE/ID3 tags from NFS/SMB files.

See http://bugs.musicpd.org/view.php?id=4270

Avoid duplicate AllocatedPath::FromUTF8() invocations in two callers.

Don't pass Path::c_str() to tag_stream_scan() which requires a UTF-8
string.

Reduce some unnecessary overhead.

Replaces StatFile(), with a portable data object.

This commit finally allows the database update to scan remote files,
e.g. using the smbclient storage plugin.  However, it is not yet
possible to configure that, therefore the feature is not accessible
yet.