Improve cover fetching speed
Factorize cover download requests even if their priorities are different.
Allows to factorize requests from the nowplaying fragment (high priority) and from the playlist (normal priority)
Always show fast scroll for 4.4

Workaround for fast scroll not being visible on 4.4 devices.
Merge pull request #333 from ssmy/master

Always show fast scroll for 4.4
Merge branch 'master' of https://github.com/abarisain/dmix into upstr
Fix titlebar when back is pressed. Fixes #332
Global album list is never a grid
Grid view is now the default view
Make MPDCommand an object and add "command_list_ok_begin"
Minor improvement for AlbumInfo
- Use the AlbumInfo check in the cover manager.
- Simplify getKey()
Improve cover request robustness : Let the cover manager triggers the cover view tag with the album key.
Avoid the use of a different album key to tag the view (in case of album key mismatch the cover notifications are ignored by the cover listeners)
Revert "Improve cover request robustness : Let the cover manager triggers the cover view tag with the album key."

This reverts commit 9555f3ecd51d9d80d49e0cf959668d13e9e4caa8.
Identify invalid albumInfo (missing artist or album) with a special tag instead of NULL.
-> Allow them to avoid receiving wrong cover notifications
-> Fix the case where you reset the cover (blank one) from the nowplaying fragment but the cover in the playlist was not refreshed.
Merge branch 'master' of https://github.com/abarisain/dmix into upstr

Conflicts:
	MPDroid/src/com/namelessdev/mpdroid/fragments/LibraryFragment.java
	MPDroid/src/com/namelessdev/mpdroid/library/SimpleLibraryActivity.java
Fix playlist cover update when changing cover from the nowplaying screen
In some cases the playlist cover was not updated (when the playlist cover is not visible when the cover download notification happens)
Add a tag to force (just once) the cover refresh when the List getView() is called.
Fix playlist cover update when changing cover from the nowplaying screen
--> Clean the code by putting the refresh informations in the model instead of adding a new cover tag.
Avoid crash (NPE) when using filter on items without album (radio streams ...)
fix merge
fix indentation of MPD.java, MPDCommand.java and MPDConnection.java

Conflicts:
	JMPDComm/src/org/a0z/mpd/MPD.java
re-enable album list covers
get full album list via queued commands for all albums of all artists