rightcontrol emits leftcontrol by default.

[bpesner]

Issue #114 explained that keyd treats both control keys as leftcontrol. No one had a use case for treating them differently. Here's one: VirtualBox uses the right control key, and NOT the left control key, as the "host key', which is used to send special commands to a Virtual Box virtual machine. I have to stop keyd whenever I want to use this function, and then restart it when I'm done. Not convenient.