Epic: support for distributing ML data sets / weights

[rklaehn]

MVP:

• support multi level directory structures Support directory trees iroh#837
• support resuming downloads Support resuming downloads iroh#838
• add progress Progress for adding a large file or dir iroh#835
• add from arbitrary dir Adding gets confused when add is not run in same directory as long running process iroh#834

Nice to have:

• get back a directory when doing get on a collection Make creating a directory the default when asking for a collection with more than 1 element. iroh#843
• provide downloaded files Provide dowloaded files iroh#875

Later:

• multi party sync Support multi party sync of large files #151
• content discovery Some kind of content discovery iroh#1342
• hole punching / derp

Related:

• using iroh from python Python support iroh#841

[rklaehn]

We got enough things now that we can demo what we have: #158

[rklaehn]

Also quite funny: the feature that I had for "maybe later", hole punching / derp, is implemented now...