Add support for CC1111

[jrozner]

Are there any plans to support the CC1111 or any other similar chips in the same family with this crate? Interested in using something like this to play with the Yardstick One from Great Scott Gadgets.

[dsvensson]

If there's a lot of similarities, it probably makes sense to separate the lowlevel module into a cc1101, cc1111, and some common module, and perhaps rename the crate to something more useful. I don't have any separate cc1111 device so I will not do it. It'd be cool if someone took a stab at it.