Rename plugin

First proposal for the rename plugin #108. It only supports cut for now and I finally settled with C because I think cleaning up the C++ interface should be handled in a different step. Please let me know if it works especially with OpenICC.
Yes, but the problem is the name of the configuration key. This way only the transformation itself has to know which config key is actually used. Anyway, I agree that this solution is suboptimal and I will replace it until a the first additional transformation is added.