svwd01: tree row icon a bit small

[SomeoneElseOSM]

Raster looks OK:
http://map.atownsend.org.uk/maps/map/map.html#18/54.14585/-1.10184

Vector a bit small:
https://map.atownsend.org.uk/vector/index.html#18/54.145848/-1.101843

It's scaled from a 32x32 in "resources/svwd01_source_icons":
~/src/SomeoneElse-vector-web-display/svwd_convert_icon_from_raster.sh ~/src/SomeoneElse-vector-web-display/resources/svwd01_source_icons/tree_row32.png ~/src/SomeoneElse-vector-web-display/resources/svwd01_icons/pattern_natural_tree_row.png