v0.8.2

• Feature: Add max depth parameter to breadth first search.
  (#27 by @phyrwork)

• Feature: Replace recursive topological sort with iterative algorithm.
  (#25 by @phyrwork)

• Fix: Fix option to merge parallel edges when creating residual graph.
  (#39 by @clue)

• Fix: Fix setting upper limit for TSP bruteforce via MST algorithm.
  (#36 by @clue)

• Minor code style improvements to make PHPStan happy,
  clean up dead code for depth first search and
  automated native_function_invocation fixes.
  (#35 and #40 by @clue and #37 by @draco2003)

• Improve test suite to support PHPUnit 6 and PHPUnit 5 and
  support running on legacy PHP 5.3 through PHP 7.2 and HHVM.
  (#32 by @clue)