v2.3.0

• kevent: refactor to remove goto statement
  (Credit: Cameron Nemo)

• Multiple fixes for compilation issues with GCC 8.1
  (Credit: Arran Cudbard-Bell)

• Add a monitoring thread that takes care of cleaning up closed kqueues
  (Credit: Philippe Wooding)

• Multiple bug fixes for leaking descriptors in kn_delete()
  (Credit: Philippe Wooding)

• Fix build errors on Linux systems that do not use glibc
  (Credit: maxice8)