Merge branch '4.1' into 4.2-beta

# Conflicts:
#	spine-flutter/pubspec.yaml

spine-flutter/CHANGELOG.md

@@ -1,3 +1,6 @@
+# 4.1.2
+* API documentation and minor cosmetics.
+
 # 4.1.1
 * Backport to 4.1 spine-runtimes branch.
 * Blend mode support.