Added code to read threshold for VP pixels from SIMCOND, also HV from SIMCOND for raddamage

To allow the adjustment of the simulated thresholds per VP sensor with conditions. For the simulation of threshold scans for CCE studies and in case we adjust the thresholds per sensor due to variable radiation damage.

Note SIMCOND change to add conditions is lhcb-conddb/SIMCOND!140 (merged) The code is backwards compatible with old conditions through.

Added some protection against sqrt(neg) and making the sensors correctly under depleted at low fluence and low HV, no effect at default conditions.