Rollback remove node unstable (further tests required for rbcks in genrl)

[alexislebis]

Check@ commit comments 69f5075

Complex rollback regarding nodes remove. Since edges are also removed through notification & not self perspective objects, it is complex to discover which prop must be rebuild and, especially cascading this change.

[alexislebis]

Major issues resides in outpouts suppression if an input linked with an NOP is altered.
Regen the outputs from an Step.oldOutputs attributes, sensible to an notification, allowing to relink auto via NOP ?

Lot of works :'(

[alexislebis]

Optimize rcbck for one RGTE.
For undo remove from a NAP PoV, snapshot NAP via .copy()