Df cleanup 2

This a clean-up of the GsfElectron DataFormat. 
Before the GED, several variables (ShowerShapes & superClusterFbrem) existed in two flavors one "classic" based on the hybrid/multi5x5 super-cluster and one "GED"-like based on the Particle Flow variables. 
Now that, in the context of the GED, we fully switched to PF, I removed the variables which are no longer needed. I removed those with the "prefix" pf and kept the original names as default.
This change is backward compatible. I was told that it is allowed for the 73X series. 
It has been tested with runTheMatrix.py -l 17.0
Hello. For quite a while, we tried to have the possibility to revert to the previous approach, that's why I was reluctant to fully remove the code. But since it seems very unlikely that we will revert, these lines can be removed if you so wish. Let me know.