v0.12.1

Update that patches a few issues.

Changed

• Improved documentation on Map::layers and Map::get_layer. (#306)
• Extend lifetime of Layers returned from GroupLayer::get_layer to the map's. (#307)

New Contributors

• @erayerdin made their first contribution in #305
• @HughHoyland made their first contribution in #306

Full Changelog: v0.12.0...v0.12.1