SUBROUTINE HWBJCO - Combines jets with required kinematics

Modified [1] routine from HERWIG [2] 5.9.

The modifications [1] are:

• The logical flag for keeping the lepton momenta fixed, DISPRO, which in the original routine from HERWIG 5.9 is set according to
  

  $${\rm DISPRO=IPRO/10.EQ.9.AND.IDHW(ICM).EQ.15}\ ,$$ (1)

  
  
  is changed to include also instanton-induced DIS, IPRO=76,
  

  $${\rm DISPRO=(IPRO/10.EQ.7.or.IPRO/10.EQ.9).AND.IDHW(ICM).EQ.15}\ .$$ (2)

  
  

• A bug concerning energy-momentum conservation in the original routine from HERWIG 5.9 has been fixed.