Apply muon radiation correction as specified in customization options
Fix check of Z momentum before and after replacement
embedding: add rfMirror option to transform input muon four-vectors

This mirrors the input muons along the plane defined by the Z axis and
the proton axis. In contrast to the rfRotation, this seems to preserve
the polarization of the Z boson.
Merge pull request #4450 from aburgm/embedding-mirror

Embedding mirror