New Extractor Idea: `scihub-dl` to auto-detect inline DOI numbers and download academic paper PDFs

New extractor idea: SCIHUB

e.g. take this academic paper for example: https://www.cell.com/current-biology/fulltext/S0960-9822(19)31469-1

If a full paper PDF is available on scihub, e.g.: https://sci-hub.se/https://www.cell.com/current-biology/fulltext/S0960-9822(19)31469-1 it could be downloaded to a ./archive/<timestmap>/scihub/ output folder.

# try downloading via verbatim URL first
$ scihub.py -d https://www.cell.com/current-biology/fulltext/S0960-9822(19)31469-1'
DEBUG:Sci-Hub:Successfully downloaded file with identifier https://www.cell.com/current-biology/fulltext/S0960-9822(19)31469-1

We could also look for a DOI number in the page URL or page html contents e.g.: 10.1016/j.cub.2019.11.030 using a regex and try downloading that.

# otherwise try downloading via any regex-extracted bare DOI numbers on the page or in the URL
$ scihub.py -d '10.1016/j.cub.2019.11.030'
DEBUG:Sci-Hub:Successfully downloaded file with identifier 10.1016/j.cub.2019.11.030

$ ls
c28dc1242df6f931c29b9cd445a55597-.cub.2019.11.030.pdf

New Dependencies:

https://github.com/zaytoun/scihub.py

New Extractors:

extractors/scihub.py

New Config Options:

SAVE_SCIHUB=True