linalg: linear algebra

The library implements, among others, computation of:
- determinant (multiple algorithms),
- reduced row echelon form,
- matrix inverse (multiple algorithms),
- solving systems of linear equations (multiple algorithms),
- gets basis from a matrix,
- gets null space of a matrix, get orthogonal complement of row space,
- gets left null space, get orthogonal complement of column space,
- nullity, rank,
- projection, and
- gets adjugate matrix.