• [web] Added an opacity slider to color pickers.
• [web] Scale bar UI improvements
• Added -scalebar style=c, a bar of segments with alternating fill, with an optional metric bar above an imperial bar (dual-units) and an align= option for lining up the two bars.
• -scalebar style=a supports dual-units: a second, shorter bar below the first.
• Fixed: projecting a world map frame to some projections could fail with "Densification error".