Added sound- and song-player to VocaluxeLib. Use it for Background-Music.
Fix for background-music-files.
Merge branch 'develop' of github.com:Flamefire/Vocaluxe into sound-player

Conflicts:
	PartyModes/PartyModeTicTacToe/CPartyScreenTicTacToeMain.cs
	VocaluxeLib/Menu/SongMenu/CSongMenuFramework.cs
Added preview-player which is used for playing preview in song-menu.
Close stream when finished (*-player)
Play song-preview instead of bg-music (if enabled) on names-, score- and highscore-screen.
Merge branch 'develop' of github.com:Flamefire/Vocaluxe into sound-player

Conflicts:
	VocaluxeLib/Menu/SongMenu/CSongMenuFramework.cs
Small bugfix.
Change preview-player. Now it's part of bg-music.
Some changes to preview-start.
Some code-cleanup.
Some improvements...
Fix video sync.
some fixes.
Added background-music-option: "Only selected song". bg-music is played on name/score/highscore screen with selected song.
Some improvements.
More improvements and fixes (nearly stable now)
Fix showing bg-video on start (if enabled)
Fix repeating of bg-music.
Draw color instead of texture when changing song (looks better)