Stéphane Micheloud

From GitHub example [`readme/Sample.scala`](https://github.com/com-lihaoyi/Ammonite/blob/master/readme/Sample.scala) I read on line 21 : ```scala "$ mkdir -p ~/.ammonite && curl -L -o ~/.ammonite/predef.sc https://git.io/vHaKQ" ``` but the contents of the sample file [`predef.sc`](https://git.io/vHaKQ)...

Blocker : see Issue [#11710](https://github.com/lampepfl/dotty/issues/11710) in GitHub project [`lampepfl/dotty`](https://github.com/lampepfl/dotty).

fixed Maven warnings, updated plugin versions

4

This PR fixes Maven warnings (e.g. missing **`groupId`**) and updates several plugin versions. We will also submit a separate PR which adds support for batch files in `component/pom.xml` and `native/pom.xml`...