BLAS and LAPACK runtime switching

Abstract Classical numerical linear algebra libraries, BLAS and LAPACK play important roles in the scientific computing field. Various demands on these libraries pose non-trivial challenge on system management and linux distribution development. By leveraging Debian's update-alternatives mechanism which enables user to switch BLAS and LAPACK libraries smoothly and painlessly, the problems could be properly and decently addressed. This project aims at introducing the mechanism into Gentoo’s eselect framework to manage BLAS and LAPACK, providing equivalent or better functionality of Debian's update-alternatives.