WIP: Mlmpfr -> Mlgmp for #385
The new version of the binding has several changes:
- the bindings are not functional so we have to take care of the allocation of MPFR variables (and Mpfrf is too incomplete to use)
- the bindings are more incomplete. For example, less_p etc are not present. An inefficient code for those is proposed (not using erange flag).
- the printing function is different so this commit proposes a new printing function
- bigarray bindings were required