Show progress bar text with GTK+ 3
Support reading tags from Ogg Opus files

https://bugzilla.gnome.org/show_bug.cgi?id=692389
Support for writing tags to Ogg Opus files

https://bugzilla.gnome.org/show_bug.cgi?id=692389
Fix reading header information from Opus files

Correctly read the sample rate and duration from Opus files.
Additionally, handle images in an Opus comment.
Update AppData for Opus file support
Error out if Ogg disabled but Speex/Opus enabled

Opus and Speex support depend on Ogg support for parsing of Vorbis
comments, used in both formats.
Rearrange Opus/Speex Ogg checks

Place the checks inside the path where Opus/Speex support is enabled, to
prevent superfluous errors.
Updated Brazilian Portuguese translation
Mention Ogg Speex support in AppData description
Update British English translation
Move main window to EtApplicationWindow object
Pass the main window to actions as user data
Move log area to EtLogArea object
Move playlist window to EtPlaylistDialog object
Move load filenames dialog to EtLoadFilesDialog
Move file search dialog to EtSearchDialog object
Move preferences dialog to EtPreferencesDialog
Move CDDB dialog to EtCDDBDialog object
Move scan dialog to EtScanDialog object
Replace strncat() with g_string_append()