Clean all projects by default

[tues]

Also add CleanTaskSpec, fix documentation and remove some unused variables/parameters.

Closes #593.

[jvican]

LGTM, thanks @tues 😄

CI is failing with:

[error] /drone/src/github.com/scalacenter/bloop/frontend/src/test/scala/bloop/tasks/CleanTaskSpec.scala:3:8: object Project is not a member of package bloop
[error] import bloop.{Compiler, Project}
[error]        ^
[error] /drone/src/github.com/scalacenter/bloop/frontend/src/test/scala/bloop/tasks/CleanTaskSpec.scala:21:6: not found: type Project
[error]   ): Project =
[error]      ^
[error] two errors found

[tues]

Yeah, I'm not sure what's wrong with that. I can clearly see frontend/src/main/scala/bloop/Project.scala file in the repo, there's a final case class Project inside, and it compiles and works fine on my machine. Also passed some of the CI builds. Really weird 🤔

[jvican]

The issue is likely that you have not rebased on top of the latest master? I merged recently #653 which moves Project around.

[tues]

🤦‍♂️ Sorry, I must've forgotten to rebase it indeed. Thanks. Also I've just realised that the builds which succeeded seem to be disabled so I shouldn't take them into account.

[jvican]

Yes, the CI will only really build either the last commit of your PR or any future commit in an open PR. Previous commits are not run because they were submitted to the repo before a PR is open. We do this to save resources.

[tues]

I mean windows extra and windows community-build always succeed because they don't seem to do anything - I didn't notice it at first and thought that some builds failed and some passed, so it must be random failure.

Anyway, windows basic failed again, but this time it doesn't look like my fault 😉

[jvican]

We're experiencing some spurious failures in the Windows CI lately. Feel free to restart the build if it happens again (I just did, looking forward to merging this).

[jvican]

Looks like I've fixed the root of our spurious CI failures, so they shouldn't happen again in the future 😉 I'll be merging this as soon as I've got green light.

[tues]

Thanks 🙂 I'm afraid I lack permissions to restart builds, though, unless you're talking about artificially amending some commit to trick CI into rebuilding automatically.