Use YAML for configuration

[alehaa]

The current configuration parser has some memory leaks and sometimes behaves a little bit buggy for invalid configuration files. In addition we need additional features for future development of PnMPI.

Instead of fixing and enhancing the current one, I'd like to suggest to use YAML for the configuration files, so we can use existing libraries instead of maintaining our own configuration parser. In addition this simplifies third-party tools (e.g. MUST), as they don't have to dump a specific configuration syntax, but may also use a YAML emitter. However, this will break the API, so the version needs to be bumped to 2.x.

[alehaa]

For the record: We've decided to switch to a YAML configuration, but provide a simple tool to convert the old configuration file syntax to the new YAML one.