[doctest-2] Add column for doctest-2

[martinmoene]

See:

• doctest roadmap
• doctest issue 4
• doctest dev branch

[onqtam]

I was planning on opening an issue about the changes (in detail) in doctest 2 once it is released :)

[onqtam]

So the main developments are:

• thread-safe asserts and logging
• C++11 only - dropped support for some compilers
• asserts can be used outside of a testing context - so the framework can be used as a general purpose assert library
• support for clang-cl

reddit release thread:

https://www.reddit.com/r/cpp/comments/99nkhw/doctest_2_released_moved_to_c11_added/

[onqtam]

Catch related: it supports templated test cases since recently

catchorg/Catch2#1437

[onqtam]

doctest 2.3.0 was just released with support for xml output.
https://github.com/onqtam/doctest/releases/tag/2.3.0

[martinmoene]

Thanks @onqtam.

Unsure if I'll be ever able to catch up again... ;)

[onqtam]

@martinmoene absolutely understandable :)