=act Make SerializationCompatibilitySpec pass on Scala 2.11.x

* The serailization format of Option has changed between Scala 2.10.x and 2.11.x
Merge pull request #15813 from akka/wip-15807-make-SerializationCompatibilitySpec-pass-on-scala-2.11.x-ban

=act Make SerializationCompatibilitySpec pass on Scala 2.11.x
=doc #15241 ClusterRouterGroup uses actor selection, remove warning
=act,clu,rem #15828 Turkish I bug
Merge pull request #15820 from ktoso/wip-15241-clusterGroupRouter-docs-ktoso

=doc #15241 ClusterRouterGroup uses actor selection, remove warning
Merge pull request #15829 from akka/wip-15828-Turkish-I-∂π

=act,clu,rem #15828 Turkish I bug
=tcp #15766: Workaround for Windows to detect TCP abort