[NewLife] add operaimport skeleton
[NewLife] import history and bookmarks from Opera < 18
[NewLife] import history and bookmarks from new Opera with webkit
[Aggregator] add rename feed possibility (fix #311)
[NSM GDrive] migrate to Util::MimeDetector (fix #1466)
[LMP] Metadata-ful playlists for #1474.
[LMP] Support metadata in m3u for #1474.
[LMP] StaticPlaylistManager migrated to Playlist_t for #1474.
[LMP] Playlist_t -> class Playlist for #1474.
[LMP] Playlist::SetProperty() for #1474.
[LMP] Save current source in custom playlists for #1474.
[LMP] More STL compatibility in Playlist for #1474.
[LMP] Playlist::IsEmpty() for #1474.
[LMP] Rely on Enqueue in ReplaceQueue for #1474.
[LMP] StaticPlaylistManager::GetCustomPlaylistPath() for #1474.
[LMP] Return static playlist path as a source for #1474.
[LMP] Respect playlist metadata on enqueuing.

Particularly, set current source according to the saved data.

Finally closes #1474.
[Core] Sane IsShown_.
[Core] Toggle window action in menu, closes #1479.
[LMP] Fix #1484.

Sometimes it's easy to shoot yourself in the foot in C++ even with stuff
like uniform initialization syntax.