Require an @ in front of all commands.

[oli-obk]

This paves the way for actually implementing rust-lang/compiler-team#512 and thus checking that the commands actually parse and aren't silently ignored.

It also is an intermediate step in rust-lang/rust-clippy#10426 for moving to the ui_test crate

[oli-obk]

I could put the @ requirement behind a crate feature or a runtime config value if preferred.

[Manishearth]

Can we not require it yet?

Behind a config is preferred if we are hoping to require it.

[oli-obk]

Done, this PR should not affect any users, except those who exhaustively construct/destruct Config.

[Manishearth]

Done, this PR should not affect any users, except those who exhaustively construct/destruct Config.

I guess that still technically counts as a breaking change. But clippy can update to a git rev temporarily.

[Munksgaard]

The failing test is unrelated to this change. Will you release a new version, @Manishearth?

[Manishearth]

Needs to be a major bump yeah? Will do.

[Manishearth]

Published v0.10.0

Hopefully one of the last publishes of this crate since I'd like to point people towards uitest over time.

[Munksgaard]

Yeah. Perhaps we should consider deprecating/archiving and pointing to uitest in the README at some point.