[FR] add inplace version of make_unexpected

[Leonezz]

There is inplace version of constructors for unexpected_type, why not also inplace for make_unexpected?

[martinmoene]

Thanks @Leonezz.

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Note to self:

Progress:

• [x] Merge PR #68.
• [x] Add make_unexpected(inplace_t...) for use with std::exception.
• [x] Add test.
• [x] Update section Algorithms for unexpected_type in Readme.
• [x] Update section A.2 Expected lite test specification in Readme.

[Leonezz]

Hi @martinmoene thanks for looking into this so quickly, I can help with the following steps if needed.

[martinmoene]

Hi @Leonezz , thanks for your offer. Perhaps easiest if I give it a go myself.