Improve album cover loader, lyrics search and streaming support

- Improve album cover loader
- Add album cover loader result struct
- Move album cover thumbnail scaling to album cover loader
- Make init art manual look for album cover images in song directory
- Make album cover search work for songs outside of collection and
  streams
- Make album cover search work based on artist + title if album is not
  present
- Update art manual in playlist for local files, devices and CDDA
- Make lyrics search work for streams
- Add stream dialog to menu
- Remove dead code in InternetSearchModel
- Simplify code in InternetSearchView

data/icons.qrc

@@ -203,6 +203,7 @@
         <file>icons/48x48/document-download.png</file>
         <file>icons/48x48/document-new.png</file>
         <file>icons/48x48/document-open-folder.png</file>
+        <file>icons/48x48/document-open-remote.png</file>
         <file>icons/48x48/document-open.png</file>
         <file>icons/48x48/document-save.png</file>
         <file>icons/48x48/document-search.png</file>
@@ -297,6 +298,7 @@
         <file>icons/32x32/document-download.png</file>
         <file>icons/32x32/document-new.png</file>
         <file>icons/32x32/document-open-folder.png</file>
+        <file>icons/32x32/document-open-remote.png</file>
         <file>icons/32x32/document-open.png</file>
         <file>icons/32x32/document-save.png</file>
         <file>icons/32x32/document-search.png</file>
@@ -391,6 +393,7 @@
         <file>icons/22x22/document-download.png</file>
         <file>icons/22x22/document-new.png</file>
         <file>icons/22x22/document-open-folder.png</file>
+        <file>icons/22x22/document-open-remote.png</file>
         <file>icons/22x22/document-open.png</file>
         <file>icons/22x22/document-save.png</file>
         <file>icons/22x22/document-search.png</file>