adds dense vector class (vec)
adds sparse vector class (sparse_vec)
adds dense matrix class (mat)
adds sparse matrix class (sparse_mat)
adds general tools
adds gaussian elimination
adds jacobi, gauss-seidel, gradient
adds conjugate gradient (standard and Lanczos)
adds weighted jacobi
adds biconjugate gradient stabilized
adds max norm to sparse/dense matrices
fixes small bug on L-p norm of dense/sparse vectors
adds missing banner on jacobi class