1.6.0

This is a minor release including a number of new features:

• Implement IsPermutationDigraph by @baydrea in #513
• Add more implications (including some implications of falsity) by @wilfwilson in #494
• Add OnTuplesDigraphs and OnSetsDigraphs by @wilfwilson in #449
• Add checks for upper/lower semimodular lattices by @james-d-mitchell in #375
• Add AsDigraph for partial perms by @james-d-mitchell in #526
• Add DigraphRandomWalk by @mtorpey in #543
• Add constructors for random digraphs with particular properties by @KamranKSharma in #531
• Add LatticeDigraphEmbedding method by @MTWhyte in #538
• Add IsDistributiveLatticeDigraph property by @MTWhyte in #528

The following improvements were also made:

• Make improvements to IsMeetSemilatticeDigraph and IsJoinSemilatticeDigraph by @MTWhyte in #556
• Add a workaround for macOS code signing issues by @fingolfin in #555