Modify THcCoinTime and THcTrigDet

1) THcTrigDet
   a) Modify code to use string vector fTrigNames to identify which of the trigger
     trigger detector TDC signals to use for coincidence timing. This
      replaces the hard-coded names. The integer array fTrigId[4] keeps
     track of the array ID in the overall fTDcNames vector that goes
      with the fTrigNames[4]
   b) The fTrigNames must be in order of SHMS ROC1, HMS ROC1, SHMS ROC2
     and HMS ROC2.
   c) Default names are "pTRIG1_ROC1","pTRIG4_ROC1","pTRIG1_ROC2","pTRIG4_ROC2"
      The parameter is t_coin_trigNames
      For example:
      t_coin_trigNames="pTRIG1_ROC1 pTRIG4_ROC1 pTRIG1_ROC2 pTRIG4_ROC2"
      This parameter is read-in and the split into a string vector fTrigNames.
   d) In HcTrigDet::ReadDatabase , all members of fTrigID array are set
to -1 then a loop over all Tdc in the trigger detector looks for match between
fTdcNames amd fTrigNames to set fTrigId. If match not found the fTrigId = -1.
   e) In THcTrigDet.h made new method Get_CT_TrigTime(Int_t ii) to be used
in in THcCoinTime to get the 4 trigger times: SHMS ROC1 (ii=0), HMS ROC1 (ii=1),
SHMS ROC2 (ii=2) and HMS ROC2 (ii=3).  If fTrigId[ii]=0 then it returns 0
otherwise returns fTdcTime[fTrigID[ii]].

2) THcCoinTime
  a) Previously used the raw trigger times and had a hard-coded 0.1 ns/channel
conversion. Now use the trigger times which already are in ns using the
ns/channel conversion set in the TrigDet.
  b) Now use the new TrgiDet method Get_CT_TrigTime(ii) to get the
trigger times for SHMS ROC1, HMS ROC1, SHMS ROC2 and HMS ROC2.