adapt boilerplate coding

[Diaphteiros]

This PR tries to improve the generic boilerplate coding in various ways, for example:

• The api folder is now its own nested submodule.
• Added a preliminary version of the cluster API.
• Use a shared struct for information that is required by run and init subcommands.
• Added standard controller flags.
• Added a dry-run mode that completes the options, but aborts before starting the actual work. This is useful for testing and debugging CLI arguments.
• Both subcommands now print the raw and the completed options during startup.
• Added coding to read one or more config files which are then merged into one single config.