Aftermath of the treacle tart

• some challenge modes show a histogram for counting faster/slower trips
• new visualization of current demand per direction at a traffic signal
• implementing some of Yuwen's UI changes: agent counter, split time/speed panel, moved functionality out of the old drop-down menus into a bottom-left tool panel, hiding debug functionality
• replaced right-click context menus with left click to open info panels
• fixed random issues reported by people from HN