General update: cleaning up the README and fixes #339, #367

[brghash]

Summary of changes

• Implemented the ability to use non-extractable types
• Improved getNodeSet and getAdjList efficiency
• Tided up the codebase, especially the README

Why

The main motivation for this PR was to improve the experience a new user has. I have personally found the README too cluttered and providing extra information that I do not require such as the implementation of the algorithms. The README should provide a point of entry into the codebase, showing the features, not providing explanations for everything, this is the role of the website and documentation. I have added in an example into the README and moved items around so as not to obscure the core information.

Related issue

• Support default serialization for pointer types #339
• Use Adjacency Matrix to populate the nodeSet. #367

Notes for reviewers

• Please check the README to confirm changes

Testing

• Added removed connectivity test
• All tests were passed

[ZigRazor]

It does not build, as you can see from CI/CD

[brghash]

I expect that the failure of the windows build is due to #530 which was present in prior versions of CXXGraph for me. I will investigate this further, soon.