Delete cruft, simplify directory structure.
Commented stuff carried over from old version.
Generic.settings: mappings for bin/, lib/, doc/ and man/

A Scala distribution is fully determined by the contents and dependencies of
the maven artifact "org.scala-lang" % "scala-dist" % version.value.

The contents of scala-dist itself is extracted to populate bin/, doc/ and man/.
The (transitive) dependencies populate the lib/ folder.

This configures sbt native packager's Universal config.

The next commit will take the jars under the javadoc classifier and extract/move
them to api/ to provide settings for the packager's UniversalDocs config.
Docs.settings: mappings for the api/ directory.

All dependencies of scala-dist under the javadoc classifier are included as
"api/jars/$artifactId-$version-javadoc.jar".

The core jars are also expanded under api/scala-{library|reflect|compiler}.

Also make constructing mappings reusable.

Needed to use updateClassifiers to get -javadoc artifacts,
don't seem to need to include the javadoc classifier in the scala-dist config.
Wix.settings: mappings for creating the MSI.

Takes the result of staging universal and universal-docs,
and creates a WIX xml description for `packageBin in Windows`
to be able to create an MSI.

We no longer distribute sources/examples this way.
We're linking to GitHub for sources.

As .bat files are published to maven using the windows line endings,
no need to convert.

PS: Would've called in Windows.settings, but that clashes with the
packager's Windows config object.