add propagator to B as well
add propagator to B as well

Implementing reification is currently still too error-prone, we need a
domain-specific language for it as well. Consider also:

   %?- X+Y#>=3 #==> B, [X,Y] ins 5..10.
   %@ B = 1,
   %@ X in 5..10,
   %@ X+Y#=_G4027,
   %@ _G4027 in 10..20,
   %@ Y in 5..10.

koryonik/swipl-devel,edechter/swipl-devel,mndrix/swipl-devel,edechter/swipl-devel,jn7163/swipl-devel,koryonik/swipl-devel,edechter/swipl-devel,mndrix/swipl-devel,jn7163/swipl-devel,edechter/swipl-devel,koryonik/swipl-devel,edechter/swipl-devel,jn7163/swipl-devel,koryonik/swipl-devel,koryonik/swipl-devel,mndrix/swipl-devel,jn7163/swipl-devel,mndrix/swipl-devel,mndrix/swipl-devel,jn7163/swipl-devel