1.7.0

This is a minor release with some new features, and some other improvements in code quality.

What's Changed

• Change test that relies on xpdf not being installed by @mtorpey in #578
• DigraphAbsorptionProbabilities by @mtorpey in #548
• Fix test files: strings and unbinds by @mtorpey in #579
• Add immediate methods for connected and strongly connected graphs by @mtorpey in #583
• kernel: fix mem leaks for permutations allocated but not freed by @james-d-mitchell in #589
• Remove references to bin/gap.sh by @fingolfin in #597
• Fix prototype warnings by @fingolfin in #598
• Added EdgeWeightedDigraph by @RaiyanC in #575
• Add AbsorptionExpectedSteps by @mtorpey in #585
• Fix a typo by @fingolfin in #608
• configure.ac: fix bashism in string equality test by @orlitzky in #613