Setting and Reading Cross fade

Changes for supporting setting and Reading Cross Fade.

Unfortunately I've done something a bit wrong when  I created my Fork for the Python-2.6 - I think I should have branched the python work - as anything I do now, seems to have those changes in! (I very clearly have no idea with what I am doing with GitHub!)

Anyway - hopefully you'll let the python stuff in - then I can tidy all my stuff up! :+1:
:-)