Changed the name of moveStackForward method
Changed artist icon
Added icon for selected artists
Set left margin for the album icon on the ArtistsActivity
Deleted unnecesary file
Changed icon_dir for a new icon an renamed it
Added an icon for the audio files
Changed song icon
Added icons for the random and repeat states
Added a list icon
Renamed the soundbox icon
Added a home icon
Added play and pause icons
Added next and previous icons