bluemap: fix exporter marker sets

The earlier version would put the markers outside the marker set

src/bluemap_exporter/exporter.py

@@ -42,9 +42,11 @@ def convert_data_to_bluemap_structure() -> dict:
             }
 
             for marker in marker_set.markers:
+                poi_markers = result[world_name][slug(marker_set.name)]["markers"]
+                track_markers = result[world_name][slug(marker_set.name)]["markers"]
                 if isinstance(marker, Point):
                     # https://bluemap.bluecolored.de/wiki/customization/Markers.html#poi-markers
-                    result[world_name][slug(marker_set.name)][slug(marker.name)] = {
+                    poi_markers[slug(marker.name)] = {
                         "type": "poi",
                         "label": marker.name,
                         "position": {
@@ -55,7 +57,7 @@ def convert_data_to_bluemap_structure() -> dict:
                     }
                 elif isinstance(marker, Track):
                     # https://bluemap.bluecolored.de/wiki/customization/Markers.html#line-markers
-                    result[world_name][slug(marker_set.name)][slug(marker.name)] = {
+                    track_markers[slug(marker.name)] = {
                         "type": "line",
                         # TODO: Calculate the median point of the track for the label position
                         "position": {