resolve "Improve dRICh optics"

Close #77 (closed)

Change log (reverse chronological order):

• update envelop for 8/25 integration requirements (see !219 (merged))
• optimized optics for 8/3 integration requirements (last commit: 49354228)
• improved spherical mirror cuts to achieve nearly 2pi azimuthal acceptance
• spherical mirror is re-parameterized, and now has focus tuning parameters to adjust the focal point with respect to the sensor sphere
• sensor sphere patch cuts are re-parameterized
• add boolean DRICH_debug_optics to quickly check optical parameters, such as focal plane and aberrations
• add documentation tags to compact/drich.xml and cleanup indentation
• use standardized ANL colors
• add optical material VacuumOptical (cf. AirOptical)

Before any changes: optical photons generated from IP, reflected off mirror; aerogel and sensors are also shown, the aerogel is non-interacting, and there are no vessel walls. Losses are seen at low eta, and the photons do not hit the sensors at normal incidence.