v0.6.0

New features

• Add MilpBipartite observation function for pre-solving (#147)
• Add Pickle support to all observation functions (#106 #152)
• Features description for Khalil2016 (#157)

Breaking changes

• NodeBipartite features have been reordered
• Changed combinatorial auctions, maximum independent set and capacitated facility location instance generators so that they produce instances of difficulty similar to those of Gasse et al. (2019) out-of-the-box (#141, #142 #150)
• Khalil2016 now returns a struct wrapping the Numpy array (#157)