EEG/CSP/BCI example

Issue #1232
The example uses data from here: http://www.physionet.org/physiobank/database/eegmmidb/
A crude downloader is included, but implementing a proper one could be a project for the coding sprint?

I don't know how to get MNE topomaps to work, so I simply used scot/eegtopo for now.

Some experimental or redundant parts of the code were left as comments for now.
Hmm, I don't think it should throw an error if that's the case -- sounds like a bug in our handling of that property. Can you give the traceback?