Added MB + PC filtering methods as local search algorithms (learn.nbr()): "gs.pc", "iapc", "fast.iapc", "inter.iapc" and "fdr.iapc"
cpquery/cpdist : new "exact" inference method
mmpc : backtracking fix (now as in Tsamardinos optimisations 6.4 and 6.5)
mmpc : always use optimized version
cpquery/cpdist: set evidence=TRUE as default value
gs, iamb, fast.iamb, inter.iamb, fdr.iamb, mmpc, si.hiton.pc : set undirected=TRUE as default parameter