AINT_TR optimization

[talassio]

Subroutine AINT_TR

1. Deal separately with B generic and B=Identinity, I(n).
2. w%B is acting as a dense Identity matrix, and is mostly not required, except for the calls to solve_spd and solve_general, some proposals follow:
3. Assembly and allocation of m0(2n,2n) and m1(2n,2n) might not be required, specially m1 where it is constituted of two diagonals identities.
4. Change max_eig so not to expect m1 and m0 but the assembly blocks a and (potentially a non identity block b)
5. Solving ( A + lambda* B ) x = b can be optimized for the case where B=I(n) and probably the allocation of b(n,n) will not be required.

https://github.com/ralna/RALFit/blob/df2478066331c494b3b9ae1e7aa081d43d6ce8d4/libRALFit/src/ral_nlls_internal.f90#L1560-L1580