cli, puppet, langpuppet: Remove puppet GAPI's

I'm currently refactoring the CLI code. Unfortunately this means a
pretty big churn in the various GAPI frontends. Since nobody is actively
using the puppet frontend code, I'm removing it for now. If someone is
actively using it, and wants to either port it to the new API, or
sponsor the porting of it to the new API, I'm happy to allow it back in.

Sorry Felix, it was a fun idea, and I loved seeing it work, but I can't
personally afford the maintenance cost of having this in right now.

docs/documentation.md

@@ -131,33 +131,6 @@ execute via a `remote` resource.
 You can read the introductory blog post about this topic here:
 [https://purpleidea.com/blog/2016/10/07/remote-execution-in-mgmt/](https://purpleidea.com/blog/2016/10/07/remote-execution-in-mgmt/)
 
-### Puppet support
-
-You can supply a Puppet manifest instead of creating the (YAML) graph manually.
-Puppet must be installed and in `mgmt`'s search path. You also need the
-[ffrank-mgmtgraph Puppet module](https://forge.puppet.com/ffrank/mgmtgraph).
-
-Invoke `mgmt` with the `--puppet` switch, which supports 3 variants:
-
-1. Request the configuration from the Puppet Master (like `puppet agent` does)
-
-	`mgmt run puppet --puppet agent`
-
-2. Compile a local manifest file (like `puppet apply`)
-
-	`mgmt run puppet --puppet /path/to/my/manifest.pp`
-
-3. Compile an ad hoc manifest from the commandline (like `puppet apply -e`)
-
-	`mgmt run puppet --puppet 'file { "/etc/ntp.conf": ensure => file }'`
-
-For more details and caveats see [puppet-guide.md](puppet-guide.md).
-
-#### Blog post
-
-An introductory post on the Puppet support is on
-[Felix's blog](http://ffrank.github.io/features/2016/06/19/puppet-powered-mgmt/).
-
 ## Reference
 
 Please note that there are a number of undocumented options. For more