Highlights:

• Extended the Hashmap interface, adding the following functions to address previous limitations and make usage more expressive:
  • hashmap_empty()
  • hashmap_contains()
  • hashmap_iter_find()
  • hashmap_insert()
• Rewrote unit tests using the C++ Catch2 framework
• Addressed some portability issues by tweaking functions (e.g. use rand() instead of random()) and updated the default language standard in CMake.
• Updated the readme to reflect the new functionality and better explain how to integrate with an existing CMake project.

Note that this release should be backward compatible with code written against v2.0.