v0.5.6

• Renamed convert_to_line_graph() to to_line_graph(), added an s parameter to the function, and added corresponding unit tests #318 (@nwlandry).
• Made the sparse warning in the adjacency_matrix() function more intelligible #315 (@nwlandry).
• Added a function for the normalized hypergraph laplacian #314 (@nwlandry).
• Added tests for draw functions #312 (@maximelucas).
• Updated the centrality functions so they more gracefully handle empty and disconnected hypergraphs #313 (@nwlandry).
• Added keep_isolates argument to the subhypergraph function #308 (@maximelucas).
• Fix: raise error for assortativity of empty hypergraph #307 (@maximelucas).
• Minor: renamed to from_max_simplices #306 (@maximelucas).