Prevented scrollbar from hiding mute button

Shifted the columns slightly when the scrollbar is visible to prevent the scroll bar from covering the mute button. No difference when the scrollbar is hidden.
Shifted column headings to match columns

Shifted column headings when the columns themselves have been shifted by the scroll bar.
Shifted column highlights to match columns

Shifted column highlights when columns are shifted by the scroll bar.
Merge pull request #550 from MyHatStinks/master

TTT: Fixed scoreboard scroll bar covering player mute button