Merge remote-tracking branch 'refs/remotes/github/develop' into develop
Remove csharp-omnisharp-curl flycheck checker

It didn't compile! A new change in the Flycheck library no longer allows
omnisharp-emacs to build a checker command using the current buffer
contents. This must be worked around separately.

There exists an issue for this at

Latest version of Flycheck incompatible with Omnisharp checker · Issue #66 · sp3ctum/omnisharp-emacs
https://github.com/sp3ctum/omnisharp-emacs/issues/66