move development to a new 1.2.x branch?

[SethTisue]

this came up at #166 and also at #163

additionally, we might consider dropping support for Java 6 and 7, which would permit us to move the build to sbt 1; see scala/sbt-scala-module#32

we might also drop support for Scala 2.11. I don't see a strong reason to do that, but it would certainly simplify maintenance going forward

[SethTisue]

additionally, we might consider dropping support for Java 6 and 7,

that part already happened, actually.

[Philippus]

I've created a new 1.2.x branch and made it the default.

[Philippus]

Regarding dropping support for scala 2.11 I don't think it's desirable. We want to support scala native which is tied to 2.11 according to https://www.scala-native.org/en/v0.3.8/user/sbt.html#scala-versions.