sqrt in dr for endcap SelectHitIndices

[slava77]

this fixes the computation of the uncertainty on r in SelectHitIndices in the endcap region. Here, after a propagation to the nominal z, check if the state is in the sensitive region and look for bins in r,phi where the hits will be searched.

(Speculative/guessing)

• expect effects at the layer edges where prop states with real uncty below 1 cm becomes smaller due to squaring and the layer can be ignored
• expect also some effects on the r-phi bin selection

http://uaf-10.t2.ucsd.edu/~slava77/figs/mic/mtv/ttbar50_CKF_vs_mkFit_pr334_drFix_98dbfd1/plots_ootb.html

• there is practically no effect on the efficiency
• the number of hits goes up a bit in the forward region, as can be seen in the hitsLayers for OOB allTracks