Improved Support for SIMD in RichDet

This MR builds on the previous work to extend the use of SIMD types in the RICH.

The primary update is to add support for SIMD ray tracing to the RichDet PD classes. I have focussed on the MaPMT class (for the upgrade) that now has dedictated SIMD methods for intersecting directions with the PD panels and detectors. For the HPD class, the SIMD method is a place holder that simply defers to a scalar loop over the scalar method. This is partly because the HPD classes are only needed in production next year, and its unlikely at this point this work will be pushed for 2018 data taking, and partly because providing a full SIMD implementation for the HPDs is actually more involved than for the MaPMTs.