OutputFilteringStrategies: Pimpl (again)

Authored by kfunk on Jan 8 2016, 9:48 PM.

Description

OutputFilteringStrategies: Pimpl (again)

History shows this class has been pimpl'd and unpimpl'd several times
now :)

This reverts commit fc24ea4e747ddaddf860d4cee315bd728f8b8d13.