Update to the latest stable version:

• fix for handling incorrect data formats by .load()
• fix regression in interactions between dense matrix subviews and sparse matrices
• fix incorrect use of constexpr for handling fixed-size matrices and vectors
• faster handling of submatrix views accessed by X.head_cols(), X.tail_cols(), X.cols(first_col,last_col)
• faster handling of element-wise min() and max() in compound expressions
• faster handling of diagonal matrices by inv_sympd(), pinv(), rank()
• expanded solve() with solve_opts::force_approx option to force use of the approximate solver