Make Volume Singelton, Code improvments, fixed live counter bug

PlayWall/src/de/tobias/playpad/PlayPadImpl.java

...as/playpad/layout/desktop/pad/DesktopPadDragListener.java

.../playpad/layout/desktop/pad/DesktopPadViewController.java

PlayWall/src/de/tobias/playpad/pad/content/AudioContent.java

PlayWallCore/src/de/tobias/playpad/pad/Pad.java

...WallCore/src/de/tobias/playpad/pad/PadStatusListener.java

PlayWallCore/src/de/tobias/playpad/project/Project.java

PlayWallCore/src/de/tobias/playpad/volume/VolumeManager.java

...src/de/tobias/playpad/mediaplugin/video/VideoContent.java