Temporarily insource Scalacheck 1.11.6

This is a temporary measure until we release Scala
2.12.0. It means we are able to release milestones,
and RCs of Scala without needing a public release of
Scalacheck. While we've never had to wait very long
for these in the past (Thanks, Rickard!) we'd like
to spare the maintainer some work betwen now and 2.12.0.

After we release Scala 2.12.0, we'll revert to a binary
dependency on the standard Scalacheck.

I have replaced the scala-parser-combinator based
command line option parsing with a quick and dirty
version.

I've had to remove scalacheck as a SBT test framework
in our build. We don't use it directly as such (instead,
it is used indirectly through `partest --scalacheck`),
and it's test discovery (which we expect to return nothing)
fails after re-STARR-ing due to an unsolved problem with
SBT's testLoader including either STARR or sbt-launch.jar
on the classpath used to discover and spawn tests.

For the record, I tried the following to no avail:

```
// Two modifications are needed from the stock SBT configuration in order to exclude STARR
// from the classloader that performs test discovery.
//   - We make `isManagedVersion` hold by providing an explicit Scala version, in order to go into the desired
//     branch in `createTestLoader`
//   - We remove STARR from the classloader of the scala instance
def fixTestLoader = testLoader := {
  val s = scalaInstance.value
  val scalaInstance1 =
    new ScalaInstance(s.version, appConfiguration.value.provider.scalaProvider.loader(), s.libraryJar, s.compilerJar, s.extraJars, Some(s.actualVersion))
  assert(scalaInstance1.isManagedVersion)
  TestFramework.createTestLoader(Attributed.data(fullClasspath.value), scalaInstance1, IO.createUniqueDirectory(taskTemporaryDirectory.value))
}

```

f

1 files changed, 3 insertions, 1 deletions

diff --git a/versions.properties b/versions.properties
index 488535c991..3b8077ab88 100644
--- a/versions.properties
+++ b/versions.properties
@@ -31,7 +31,9 @@ scala-asm.version=5.0.4-scala-3
 
 # external modules, used internally (not shipped)
 partest.version.number=1.0.16
-scalacheck.version.number=1.11.6
+# We've embedded these sources in partest-extras for now. After 2.12.0 is released
+# we can switch to a public release.
+# scalacheck.version.number=1.11.6
 
 # TODO: modularize the compiler
 #scala-compiler-doc.version.number=1.0.0-RC1