Pixel digi

cleanup and improvements in computational performance mostly connected to cluster 2 rechit for pixel.
Fixed also a couple of longstanding bugs. It affects the cluster error (mostly in local x) for about 1% of the clusters.

next would be to test a faster version of SiPixelTemplate::qbin that does not interpolate

p.s.
why things such as
RecoHI/HiCentralityAlgos or /DQM/Physics, SUSYBSMAnalysis/HSCP or DQMOffline/JetMET
depend on details of the PixelTopology remains a mistery to me