Fix #1216: Deprecate inheritance from Scala collection wrappers
Fix #1210: Explicitate warning that packager will be removed
Merge pull request #1257 from gzm0/prepare-0.6

Prepare 0.6
Merge pull request #1258 from gzm0/backports

Backports 0.6.x to 0.5.x
Fix #1211: Warn if non-forward compatible @JSExport is used
Merge pull request #1262 from gzm0/warn-jsexport

Fix #1211: Warn if non-forward compatible @JSExport is used