Fix incremental compilation when a Scala project depends on a Java project (#414)

* Upgrade ammonite to 1.1.2-30-53edc31

This is mainly to get https://github.com/lihaoyi/Ammonite/pull/851 which
should reduce the amount of unnecessary work done by incremental
compilation in the Mill build. This requires some code changes since
this means we now depend on a more recent version of coursier, as a
side-effect this means that we do not depend on scalaz anymore.

Also use the same ammonite version in the Mill build and in
ScalaModule#ammoniteReplClasspath.

Also remove an incorrect dependency in the caffeine integration test.
This was always wrong but did not start failing until this commit,
probably due to dependencies appearing in a different order on the
classpath.

* Rename ScalaWorker to ZincWorker

Starting with the next commit, it will be used in Java-only projects
too, so the name is misleading.

* Upgrade to Zinc 1.2.1

* Fix incremental compilation when a Scala project depends on a Java project

Before this commit, JavaModule#compile simply called javac
unconditionally, thus generating new classfiles every time. But if a
Scala project depends on a Java project, this will throw off the
incremental compilation algorithm which will unnecessarily recompile
files. To avoid this we now use Zinc to compile Java projects too (as a
bonus this means that Java compilation becomes incremental). This
required some refactoring in ZincWorkerImpl to be able to compile stuff
without having to pass Scala-specific options.

The issue solved by this commit could be reproduced by running in the
Mill repository:

$ mill main.compile
$ mill -i
@ main.compile()

and observing that before this commit, the `main.compile()` call ended
up recompiling code.

1 files changed, 2 insertions, 2 deletions

diff --git a/scalalib/test/src/mill/scalalib/dependency/metadata/MetadataLoaderFactoryTests.scala b/scalalib/test/src/mill/scalalib/dependency/metadata/MetadataLoaderFactoryTests.scala
index 8187976c..4c2206b8 100644
--- a/scalalib/test/src/mill/scalalib/dependency/metadata/MetadataLoaderFactoryTests.scala
+++ b/scalalib/test/src/mill/scalalib/dependency/metadata/MetadataLoaderFactoryTests.scala
@@ -32,7 +32,7 @@ import coursier.Fetch.Content
 import coursier.core.{Artifact, Module, Project, Repository}
 import coursier.ivy.IvyRepository
 import coursier.maven.MavenRepository
-import scalaz.{EitherT, Monad}
+import coursier.util.{EitherT, Monad}
 import utest._
 
 object MetadataLoaderFactoryTests extends TestSuite {
@@ -45,7 +45,7 @@ object MetadataLoaderFactoryTests extends TestSuite {
       }
     }
     'ivyRepository - {
-      val ivyRepo = IvyRepository(
+      val Right(ivyRepo) = IvyRepository.parse(
         "https://dl.bintray.com/sbt/sbt-plugin-releases/" + coursier.ivy.Pattern.default.string,
         dropInfoAttributes = true)
       assertMatch(MetadataLoaderFactory(ivyRepo)) { case None => }