8.1.1 flag_pc(xflag,xdata,n_phase,n_channel,low,high,ii,jj,kk)

flag_pc $<$ chanana $<$ BoaChanAna.f90

! NAM: flag_pc  (sub)
! DES: set flag for data point of given channel if data <low or >high 
! INP: 
!      n_ph    = phase: 0=differences,1=one,2=two
!      n_ch    = channel number for which data to be flagged. 
!                NOTE: python N corresponds to fortran N+1.
!                      channel 1 is index 0 in python arrays. 
!      low     = lower limit 
!      high    = upper limit
! OUT:
! HIS: FB040303  change to _p
!      FB040426  make indexing consistent with python