How to add a module global parameter

In this git commit, two new module parameters are being added to omfile. They replace some hard-coded defaults for action parameters. This commit shows

• how to add module parameters
• how to apply them as defaults to action parameters

Please be sure to note the difference between module and action parameters.

Note that the new module parameters do not modify behavior of legacy (pre-v6) config statements. This is done intentionally to prevent complication with upward compatibility of old-style config files.

This commit is intentionally minimal in order to show the most important aspects. For a proper commit, the ChangeLog as well as the module documentation need to be updated as well. An example commit for the doc parts can be found here. It is usually suggested to do both tasks in a single commit (as they obviously closely belong together).