Get FUSE-T support stable

[anacrolix]

#2 and #3 added support for FUSE-T thanks to @macos-fuse-t. There are some rough edges to fix, this is a catch all issue for them as they come up.

• Allow concurrent mounts

[anacrolix]

@macos-fuse-t I see the os.File at the package scope were due to the GC closing file descriptors on us prematurely. I'm working to fix that.

[anacrolix]

I've fixed that in d6c2a29.

[anacrolix]

@macos-fuse-t I've progressed this significantly. Feel free to fiddle with it, in particular you can set
FUSE_FORCE_BACKEND=osxfuse or FUSE_FORCE_BACKEND=fuse-t to compare tests. go test -race -v ., and it's worth running the tests in github.com/anacrolix/torrent/fs, as well as test.sh from that same package (runs a production test which I have gotten working after some changes to torrent/fs to support FUSE-T idiosyncracies. Run the anacrolix/torrent stuff from anacrolix/torrent@master...fuse-t.

[macos-fuse-t]

@anacrolix Thanks for the effort

[anacrolix]

It's not stable enough to use by default in anacrolix/torrent. I think this package still needs more work @macos-fuse-t

[macos-fuse-t]

Any concrete issues?

[anacrolix]

Nothing I could pin down. I'll put them here if I find anything. If you run with the instructions above you might get some insight.

[macos-fuse-t]

So just run the tests from github.com/anacrolix/torrent/fs and test.sh?

[anacrolix]

Yes

[anacrolix]

Was anyone able to do those tests?

v0.3.1 is now released.