Add a way to easily download Evopedia archives

[mossroy]

It's a bit complicated for the end-user to download an archive separately (with a bittorrent client), then to put it on the sdcard of its phone. It might be a blocker for some.

An idea would be to put a bittorrent client inside Evopedia (as in the original application). The archive could be downloaded directly from it.
Maybe using http://btappjs.com/ or a similar library.

In any case, downloading all these GBytes will take numerous hours, and should be done through an unlimited internet connection (i.e. usually WiFi instead of 3G/4G)

[mossroy]

I was told that btappjs would not enable me to download with Bittorrent in pure javascript.

[mossroy]

https://github.com/kzahel/jstorrent is a pure javascript bittorrent implementation.
It currently only works on Chrome but might be ported to Firefox with DeviceStorage API.
I suggested the idea to the main contributor. He liked the idea : kzahel/jstorrent#15 (comment)
But, since then, all the code/issues have disappeared from Github, "due to licensing issues". I hope this is only temporary.

It would have been a way to delegate the downloading (through WebActivities), or to integrate it in the application (if the license permits it)

[mossroy]

I close this issue as "wontfix" : the Evopedia archive format is now deprecated.
ZIM files can be downloaded through HTTP (and also via Bittorrent, but it would be easier with HTTP when downloading from a device). See #114