Added options, system includes, funcs and libs

[Two4]

No description provided.

[Mizux]

Why adding gmp.h ? not sure we need it...

[Two4]

Why adding gmp.h ? not sure we need it...

Windows typically doesn't have it, even if it has libgmp.dll. Compiling with GMP is much more efficient, according to the GLPK docs, so I'd like to make it a default option if possible

[Mizux]

I find this one more KISS https://github.com/dune-project/dune-common/blob/master/cmake/modules/FindGMP.cmake
especially the Modern CMake way to expose GMP::gmp and GMP::gmpxx

also there is port for gmp on vcpkg https://github.com/microsoft/vcpkg/tree/master/ports/gmp but it would need some cleanup too

[Two4]

Still a mystery error on the MSBuild CI workflow, but everything else is completing 100%. MSVC build are working fine on my machine, but we've all heard the ol' "it works on my machine" schtick before

[Two4]

This was unintended, I renamed the branch - didn't think it would delete it