✅ re-added tests for algorithms

Overworked library toward 3.0.0 release

🚨 remove C4996 warnings #872

This reverts commit 920f64c0.

Update required all CHECK_THROWS_AS macros to pass the exception type without reference, because this is now done by Catch2.

- Added recent contributors to thanks list.
- Linked PGP key for private mails.
- Updated compiler list.

- All hex literals use upper case letters after the x.
- Fixed sime typos.
- Documented some more functions.

These were the remaining direct calls to alloc.

💥 throwing an exception in case dump encounters a non-UTF-8 string #838

As we guarantee proper UTF-8 before, we do not need to cope with it later.

We had a lot of issues with failing roundtrips (i.e., parse errors from serializations) in case string were stored in the library that were not UTF-8 encoded. This PR adds an exception in this case.

📝 fixing documentation #867

The example in the documentation on how to "force" an array of arrays was wrong since the first release. Fixed the documentation and added checks for the README unit tests.

iter_impl template conformance with C++17

Std allocator conformance cpp17

cmake: use BUILD_INTERFACE/INSTALL_INTERFACE

fixed conformance with C++17, some members of allocator are depricated and should be used via allocator_traits

to/from_json: add a MSVC-specific static_assert to force a stacktrace

Add .natvis for MSVC debug view