fix a bug in calculating clarity loss as sample weight is specified.
0.5.5
support for monotonicity & convexity support manually selected interactions (in addition to selected ones).
0.5.4
1. add support for convex and concave constraints (new arguments, i.e., convex_list and concave_list); 2. change the way of pruning main effects and pairwise interactions, i.e., from the percentage of the optimal loss to the percentage of loss range.