Adding motor imagery part of the Lee2019 dataset

[AliAbdulHussain]

I have added a new motor imagery dataset called Lee2019 also known as BMI dataset or OpenBMI dataset.

[AliAbdulHussain]

While building the documentation I ran into 2 problems: The first is librosa/librosa#1153 which was fix by following the same post advice (turning False into None), the second is explained in sphinx-doc/sphinx#7420 which was fix by sphinx-doc/sphinx#7420 (comment).

[sylvchev]

Thanks @AliAbdulHussain !
This dataset is really nice, especially with the fact that the data are available on all 3 paradigms (MI, SSVEP and ERP) for each subjects. I could help you to add the SSVEP and ERP paradigm if you want. As discussed during the office hours, we have added the support for black with pre-commit. You may need to open a new PR to start from the updated master branch. Do you want some help to do that?
Right now, there is a problem with the downloading of the dataset, as it is stored on a FTP server and the MNE functions could not handle this protocol. Does that work on your installation?

[AliAbdulHussain]

Thanks, @sylvchev for looking at my PR. I completely forgot about this. When I was first using moabb, I needed to download Cho2017 which has the exact same problem. I modified the _fetch_file(.) to allow for ftp downloads (i.e. added 'ftp' to line 104 (if scheme not in ('http', 'https'))). With this simple change, the rest should work perfectly. Sorry for the inconvenience caused.

About the SSVEP and ERP, I'll have a look at them. I'll let you know if I need any help.

[sylvchev]

The PR #170 is a rebase of this PR. It is merged! Thanks @AliAbdulHussain for your contribution. I'll try to add other datasets from Lee (SSVEP and ERP) in a separate PR.