wip/gmm 4.0.0 NetBSD

Gmm++ is a generic C++ template library for sparse, dense and skyline matrices. It is built as a set of generic algorithms (mult, add, copy, sub-matrices, dense and sparse solvers ...) for any interfaced vector type or matrix type. It can be view as a glue library allowing cooperation between several vector and matrix types. However, basic sparse, dense and skyline matrix/vector types are built in Gmm++, hence it can be used as a standalone linear algebra library. Interfacing a vector or matrix type means writing "traits" objects called "linalg_traits", which describe their properties. The library offers predefined dense, sparse and skyline matrix types.