Transformation to "group" and "de-group" higher arity operators

[daemontus]

The current plan is to support and/or as operators with arbitrary arity, since this makes a lot of sense for DNF/CNF normal forms. However, this also means that (x & (y & z)) is a different formula than (x & y & z). This is fundamentally fine, but we should have a way to contract/expand such high arity operators. That is, at the very least have a function which will "merge" all and/or operators where possible, and also have a function that will "break them up" into normal binary operators.

One reason why we might want this is that not everything may work with the higher arity representation, and in some cases we simply need to output a representation with only binary operators.