JSON Endpoint: Handle content-type-less requests.
Add Optional::emplace() - as in std::optional.
Simpler construction of Tagged structures.
Merge pull request #35 from LEW21/optional-emplace

Add Optional::emplace() - as in std::optional.
Merge pull request #36 from LEW21/tagged-constructors

Simpler construction of Tagged structures.
Merge pull request #34 from LEW21/json-endpoint-no-type

JSON Endpoint: Handle content-type-less requests.