Implement name to part reference change (ugly)

Implement name to part reference change (ugly)

This commit introduces the swap from a part name to a pointer to a part.

It also implements the p and n FETs as parts in a way that I consider
ugly - there is a lot of stuff that WILL BREAK if Libft changes the
implementation of the underlying structures. I explain myself in a
comment directly adjacent to the ugly code but will reiterate here.
The 42 Norm only allows static constant globals I was not able to define
the FETs as such. So I fit them in a static variable of a function. And
so that I don't have to release the memory (Norm mandates clear
Valgrind output) I try to fit it on the stack.

This should be quite easy to refactor if one decides not to comply with
the Norm.