adjust Searchactivity
show artists in albums list
fix mopidy behaviour (missing listallinfo)
compare albums by names only to fix duplicates on mpd 0.18
remove songs that don't belong to an albumartist album

mpd >=0.18 puts them in as it takes the artist as the albumartist
if that is not defined
fix string comparisons
add strings for unknowns
 don't filter unknown artists/albums and show them on top of lists

Conflicts:
	JMPDComm/src/org/a0z/mpd/Artist.java
	JMPDComm/src/org/a0z/mpd/MPD.java
	JMPDComm/src/org/a0z/mpd/Music.java
show unknown album text in album grid, too
show unknowns in search results, too
show "Unknown Artist" in SongsFragment header
don't list unknown albumartists for "unknown artist"
in Music, initialize Album with "", too
When browsing genres, show only albums belonging to the selected genre

fixes #263
sort Items by name instead of mainText, allow "" in ArrayIndexerAdapter
don't show cover placeholder for unknown albums
show artist in album grid