Set proper characteristics for used PMT types

[marc1uk]

Before electronics threshold should be given by Dark Rate times conversion factor:
e.g. ~ SK-I: 4.2 kHz
Measured DN with 0.25 pe threshold:
e.g. ~SK-I: 3.4 kHz
In WCSim SK PMTs currently use 4.2 Hz after the threshold, although this should probably be 3.4 kHz (see issue 134 WCSim#134).
Adjust properly for Watchboy, LUX, HQE, LAPPD etc.

[marc1uk]

Also proper QE arrays and collection efficiency arrays

[marc1uk]

Also proper 'Hit Efficiency'? Related to charge from a pe and how often this is > digitization threshold?

see:
https://github.com/marc1uk/WCSim/blob/annie/src/WCSimWCDigitizer.cc#L252
https://github.com/marc1uk/WCSim/blob/annie/include/WCSimWCDigitizer.hh#L88
https://github.com/marc1uk/WCSim/blob/annie/src/WCSimWCPMT.cc#L54

[marc1uk]

pe's from a given hit defined in PMT: rn1pe
Time resolution of PMT defined by PMT->HitTimeSmearing

[marc1uk]

e.g. R7081 HQE (R7081-100) datasheet says dark rate typically 8kHz, programmed as 3kHz, with conversion factor 1.367...How does this tie up?