for 1.2.x, drop Scala 2.11 support (including Scala Native)

[SethTisue]

Scala Native support could be re-added once SN supports Scala 2.12 and/or 2.13

[SethTisue]

@Philippus It just seems like a maintenance burden to me. I don't have my heart set on merging this, though. wdyt?

2.11 support would remain in place on the 1.1.x branch

[Philippus]

I'm okay with it, but this will not cause problems for https://github.com/lightbend/ssl-config for example?
If there is an important bugfix we could always backport it to the 1.1.x branch.

[SethTisue]

I think ssl-config could themselves be dropping 2.11 support at this point. But anyway yeah exactly, the 1.1.x branch still exists, in the unlikely event we need it.

[SethTisue]

Hmm.... 2.13 support for Scala Native support was merged today. I hadn't anticipated that happening so quickly after 2.12 support landed.

So perhaps it would be better to wait a little while longer for a Scala Native release, then redo this PR to drop 2.11 but without dropping Scala Native.

[Philippus]

Awesome! Good that I stalled on reviewing. ;)

[SethTisue]

okay, closing for now, we can always reopen later