Allows creating of callout lines (or bubble callouts) which
link the text to a map location. To create a callout, users
select the text item and then drag out the central x node
to the desired callout end point.
Callout styles can be modified through the layer styling panel.
Can render SVG or raster images as items in an annotation layer.
Options are present for:
- Locking the picture's aspect ratio
- Drawing with a background symbol
- Drawing with a border symbol
- Linked or embedded pictures
