fix: draw picture icons unmodified and slice 2D marker sprites

A marker icon is either a monochrome glyph, whose silhouette is filled with
the category colour, or a picture that already carries its own colours.
Both were being flattened to a single colour, which left RuneScape's pins as
plain coloured circles: the sprite fills its whole cell, so tinting it kept
only the outline. The catalog now says which form an icon takes, and pictures
are drawn as they are.

Marker sprites also come as a grid rather than a single strip, and the pitch
between cells is not always a whole number of pixels. Both offsets in
background-position are read instead of only the first, which was the x and
therefore zero for every cell of a column. Temtem publishes exactly that
layout and had no icons at all: 139 of its 139 categories fell back to
drawing their initials on the map, and 138 now have their own.

Remaining gaps are individual keys the archive never captured a glyph for:
armor (Fallout), landmark and five Forza food icons, tad (Marathon), other
(Skyrim), region and zora_monument (Zelda), placeholder_0 (Temtem).

commit

5d4078f4f59e2c6c1a7a691441d6ddab0fcdddfd

parent

12650e5c55028df1f0e6916e73e88929dd7096f5

author

Dami <dami.etoile@gmail.com>