fix macOS CI tests

another `noreturn` fix

fix some usages of `expect` and `expectErr`

Fix returning value from `expect`

Merge pull request #4 from KostiantynTokar/forward

Proper forwarding

Merge pull request #3 from KostiantynTokar/patch-1

Allow @System pred

Merge pull request #2 from WebFreak001/patch-1

Improve description for dub search discovery

Drop support for too old compilers..

usability tweaks of `orElse`

travis-ci tweaks