Runtime improvements, bug fixes, improved visualization for instance-cost-sensitive

equivalent points bound for cost-complex-accuracy
purification bound for sparse objectives
precompute feature pairs per instance to speed up d2-search
filter features for d2-search
skip zero-cost labels for d2-search
improve sim.lb execution
progress tracker for verbose execution
search for trees of increasing depth
precompute the equivalence of two feature vectors with unique vector ids
improved the visualization of instance-cost-sensitive trees
bug fix: check if a feasible solution exists (not optimal means still feasible)
bug fix: computing the combination of the left and right lower bound previously ignored the cached left and right lower bound
bug fix: ignore the time limit in the reconstruct phase
bug fix: pass the optimization task in the STreeDRegressor (was previously ignored)
bug fix: do not recompute the hash for dataviews
bug fix: off-by-one error for the subtract UB procedur

Provide feedback