Remove unused dependencies - review examples and tutorials

[sylvchev]

closes #180

This issue is connected with the problem in documentation generation #173 as wfdb silently fails to download the file and when the example code extracts MNE epochs from downloaded files, they are empty.

I contacted Dr. Spiridon Nikolopoulos, that posted the MAMEM dataset on figshare. Unfortunately, these are only big rar/zip files that contain .mat files for each session/subject. I worked on the figshare to upload the separate files, it is okay for MAMEM 2 and 3.

I added all the code to download and open mat files instead of wfdb format. The data and labels obtained with mat files are similar to those obtained with wfdb.

This PR also introduces some new code to download dataset without using MNE internal fetch function. As they told us, it would be deprecated. They recommend to use pooch. I added helper function in download.py to get FigShare file using pooch.

There is still a problem with MAMEM 1 dataset, because of an internal error of FigShare. Maybe it is possible to merge this code without waiting for full support of the MAMEM 1.

[sylvchev]

The figshare issue is solved. I could remove the wfdb dependency. Also, download.data_path that relies on MNE _fetch_file is now deprecated in favor of data_dl (that relies on pooch.retrieve). The data_dl allows to support the download through http, https, ftp and sftp. This allows to solve the FTP issue #77 for Cho2017 and Lee2019. Also, I updated the Wang2016 to use FTP, thus downloading directly mat file instead of rar archive. This allows to drop the pyunpack and patool dependencies. While replacing the data_path by data_dl, I corrected a regression error on Weibo2014 dataset (the ch_names was incomplete causing error).

I added the request dependency for figshare download support, it is important as MNE is will not provide support for fetching datasets.

In order to ease the documentation building, I reduced the number of subjects use in the examples and tutorials. Also, I picked smaller datasets and tried to reuse the same datasets across examples to limit the number data to download. I corrected the Result class, because session and subject field where uncorrectly typed as byte instead of string, resulting in wrong displayed information in example plots. I corrected the default storage of hdf5 file for Result class, using an MNE compliant path and documenting it in the tutorial. The tutorials file encoding was incorrect (part DOS and Linux end-of-line) and it is homogenous now.

Closes #77

[sylvchev]

This code is stable and is ready to merge. I tested it against all examples and tutorials.

@jsosulski @v-goncharenko or @ErikBjare
Do you have the time to double check this PR? We could move to fix #174 afterwards.

[jsosulski]

I can take a look on the weekend!

[jsosulski]

Looks good to me aside from some minor comments. :) thanks

[jsosulski]

I guess this is mamem specific, but why is the diff compared to 382?

[sylvchev]

Ok, I'll merge this one!