To allow Spring Boot projects to easily integrate with picocli. Main target is Spring Boot 2.

Very high level goals:

• starter module (to facilitate dependency management for users, in my understanding this is basically just a pom.xml)
• IFactory implementation that gets object instances from Spring ApplicationContext. Something similar to MicronautFactory for the Micronaut dependency injection container. (This should fix Spring not used when calling parseWithHandler #658.)
• Runner API to start a picocli-based application in one line, similar to PicocliRunner in Micronaut, but enhanced for the new picocli-4.0 execute API that allows further configuration of the CommandLine instance and returns an exit code.