Add more output path options.

It is now possible to create a complex directory structure for outputted files.
For example:

output_path=output/%match_group_id%
match_output_path=%output_path%/%match_id%
steps_output_path=%match_output_path%/steps

By default all these have the value of output_path, but can be overridden... Ofcourse this requires some thinking from the user, since there is no check for infinite include loops... output_path=%output_path% for instance.