Accelerate GMRES (and other linear solvers) using Machine Learning in C++

This is the C++ version of the code here: https://github.com/ML4FnP/GMRES-Learning

This is very much a work in progress -- we are actively adding features/refactoring experimental code. If you have any questions, please feel free to reach out to Johannes Blaschke: https://www.nersc.gov/about/nersc-staff/data-science-engagement-group/johannes-blaschke/