Fixed downloading, and added a notebook to demonstrated downloading

[mitchellostrow]

I wasn't able to get the code to load and process the bwm PETH data, so I wrote up a quick fix. The code now successfully loads and runs umap, raster map, pca, etc on the feature vectors for a test subset of the data directly through the notebook, as simply as possible. Note that I haven't gone through and checked that this method is directly equivalent, as I wasn't able to get the previous code loading data. When running that code on get_all_PETHs()
, I got the following error:

ALFObjectNotFound: trials  
The ALF object was not found.  This may occur if the object or namespace or incorrectly formatted e.g. the object "_ibl_trials.intervals.npy" would be found with the filters `object="trials", namespace="ibl"

If there is an easier way to fix, lmk and I will revise the notebook and code accordingly

[mschart]

Great, glad you had a look! We currently revise the whole manuscript substantially, find the latest code in the develop branch. The core ideas are the same, however we changed the PETH types, to avoid low trial number artifacts (now we require at least 10 trials for any PETH type, for a session to be included).