Make the compiler doc tool work on 2.13

[som-snytt]

The doc data task runs under sbt's 2.12 regime. Either get the task to fork with the build product, or just restore the subproject.

Also, restore other manual tweaks to the previous doc in a way that doesn't require manual tweaking.

[lrytz]

The doc data task

What task is that..?

[xuwei-k]

https://github.com/scala/scala/blob/9460838f22488d1d05a56b53af334e7855bb4b29/build.sbt#L889

[som-snytt]

Previously, without knowing what I was doing, I thought the previous subproject was a bit heavy weight. I hope there is an easy way to define a task that runs build/pack/bin/scala project/GenData.scala or what have you. It doesn't necessarily need to be automated, since it's generating a file for the docs project. Maybe the source file should go in the top level tools dir.

[som-snytt]

Hey, somebody edited my title! Anyway, retronym asks also to update sbt parser and bash completion. I intended to get to this during GSOC, but now it will be, "Do I go trick-or-treating or make progress on that bug?"

[SethTisue]

@som-snytt perhaps you could offer some advice and/or assistance on https://github.com/scala/scala-lang/issues/1105 ?

[som-snytt]

Now it's, "Will I spend another Valentine's Day coding?" Plus, it's a Friday night this year.