Allow markup in license labels
Some maps have multiple sources they need to attribute. For example, the map style I'm developing needs to attribute both OpenStreetMap and the OpenMapTiles schema. This is difficult because we only have one license-uri
property per map source.
To fix this, we could add a boolean license-use-markup
property to ShumateMapSource. The license_label
GtkLabel in ShumateLicense would use markup, and map sources that don't have license-use-markup
set would use g_markup_escape_text
before inserting the text into the label.