Fix conversion from fill-opacity to CSS

[1ec5]

Unmultiply RGB components by the alpha component. If fill-opacity is unspecified, use fill-color directly in CSS. Apply fill-extrusion-opacity to the whole feature, not just its fill.

Fixes #664.

[ZeLonewolf]

I zoomed to the following location (localhost link)

I don't seem to be seeing intermittent water show up here.

[1ec5]

I don't seem to be seeing intermittent water show up here.

These are river areas, not lake areas. #632 didn’t add a legend entry for river areas because they would be redundant to river lines. If this is confusing, perhaps there needs to be an ability for a single legend entry to be depicted as both a swatch and a line, each occupying half the table cell. It’s possible that river areas were showing up by mistake until #637 tweaked the filters on these layers.

[ZeLonewolf]

Looks good on a lake, then. Intermittent river areas are probably worth a legend entry, separate from the river area + river line for a normal river.

[1ec5]

Intermittent river areas are probably worth a legend entry, separate from the river area + river line for a normal river.

Yeah, this needs more thought. The legend doesn’t depict river areas at all, regardless of intermittency. It isn’t difficult to add a separate entry for river areas, but the difficulty is what to call it and how to visually distinguish it from the entry for lakes and ponds.