Merge pull request #102 from flokuep/develop

Some minor improvements
Simplify Songmenu (only selected and preview numbers)
More consistent handling of mouse and keyboard selection of songs
Better name for function
Avoid playing background music in sing screen
Fix selection changes
Fix showing/hiding of song menu
Fix medley and short song gamemodes
Better handling of assembly loader
Rename File/Folder name variables to distinguish them from real (full) paths
Make sure full path is used everywhere (if I didn't miss anything)
Merge branch 'develop' of git://github.com/Vocaluxe/Vocaluxe into develop
Fix crash at song end
Merge branch 'develop' of github.com:Flamefire/Vocaluxe into develop
Fix wrong song name showing in party mode
Fix crash on closing a sound stream
Remove redundant names in playlist functions
Fix handling of playlist IDs
Merge branch 'develop' of github.com:Flamefire/Vocaluxe into develop
Fix Server
Enable hiding the Server QR-Code Popup
Fix categories not showing on start
Fix NPE with few songs in category