This partially fixes multiple media players in LibVLC. This also
removes a few run-away var_Create() in doVolumeChanges().

May Ronald S. Bultje be praised for this.

May Kostya Shishkov be praised for this.

Initial patch by Gerrit van den Hanenberg.

This fixes, e.g. garbage OSD display when toggling mute with the hotkey.

This is not legal (even if it works on all platforms). Also, this fixes
a warning.

PARENTAL ADVISORY: explicit hack

This should allow volume control to (somewhat) work in LibVLC.
Unfortunately, it will still be buggy when there are multiple players.

This will probably never work for LibVLC.

This reverts commit cc4cabdf.

- searchLineEdit: proper clearing
- locationBar content will not affect searchLineEdit size

It closes the other part of #3161.

It partially closes #3161.