MLlib, exposing special rdd functions to the public

I'm up to implementing algorithms using a sliding window.
The solution already exists in
/spark-mllib/src/main/scala/org/apache/spark/mllib/rdd/RDDFunctions.scala
but is not accessible due to a private[mllib] limitation.
I think exposing this part of the mllib to the public would be very helpfull because the functionality is also interessting for external developers.

This is my first Ticket at the Spark Jira. I hope my argumentation is clear.