Decisions where not added in instantiations

       dolmen: c47a8109851cd4a0b14c8e45124330d3d08154d9

  and print better algebraic number

Fix some imprecision

  Memorylimit with 20G reached on exemple of union.mlw

    terms can be grouped and scheduling of those decisions freezed

In order to not keep some and simplify the debug gui

      Egraph.Ro.t is Egraph.rt and  Egraph.t is Egraph.wt

Use more first class function for attaching event. The second part scheduled
keep the Dem.t type.

    and a debugging flag --debug-flag contradiction

       Push only allow to add at the end, not dequeue

       q.mlw proved only by colibri2_stage0

    - Handle a little of floor and ceil as (- (floor (- x)))

    - But in order to be really useful in fourier factorization is needed

  - perhaps less efficient but normalization can also be used
  - allows to remove CC terms from parents information
  - separately fix a missing find_def in fourier

  - deduce only contradiction