Consolidating varreplacer's internal stat update code
It's not NonRed, it's Irred(undant)
Wrong naming. Fixing: NonRed->Irred(undant)
Fixing a compiler warning
Refactoring varreplcer for more sane, smaller functions
Adding a function to allow adding unit clauses to drup

This makes things a lot easier to code
Cleaning up a bit of the DRUP code
Fixing drup code -- after rename, compile was not tested
We cannot parse XORs so this fuzzer has to be disbled for the moment
Using LGPL 2.0 not 3.0. It's more permissive, and 3.0 can be problematic

There have been too many wars, I don't want to be part of them. 2 or
later means also 3.
Removing useless comment, it was hopelessly out of date
Refactoring preformReplace() to use a sub-function for clarity
Inverting the two sides of the equality

It's more clear this way