core: bugfix: bootstrap random permutation

the random permutaton for bootstrap peers was not working as
intended, returning the first four bootstrap peers always.
this commit fixes it to be a random subset.

This commit includes a poor attempt at a changelog.

fsrepo migrations

The "daemon.lock" was really a repo.lock, as the cli also took it
and the purpose was any process mutex. This is part of the 1-to-2
migration, and has already been handled in
https://github.com/ipfs/fs-repo-migrations/tree/master/ipfs-1-to-2

Improved the repo migration errors to provide instructions
to the user.

This changes .go-ipfs to .ipfs everywhere.
And by the way this defines a DefaultPathName const
for this name.

License: MIT
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>

WARNING: No migration performed! That needs to come in a separate
commit, perhaps amended into this one.

Migration must move keyspace "/b" from leveldb to the flatfs subdir,
while removing the "b" prefix (keys should start with just "/").

This allows replacing the datastore without needing to write Close
through to every wrapped datastore.

FSRepo.Open is dead since fdd1cd8d

- handle error on "/ipns/"
- bounds-check, otherwise might cause a panic

cmds/add: silent error fix

Iss750

Move IPNS resolutions into the core library via the pathresolver.go
file. Fix the CLI commands to leverage this core component.

remove debugerrors

We now consider debugerrors harmful: we've run into cases where
debugerror.Wrap() hid valuable error information (err == io.EOF?).
I've removed them from the main code, but left them in some tests.
Go errors are lacking, but unfortunately, this isn't the solution.

It is possible that debugerros.New or debugerrors.Errorf should
remain still (i.e. only remove debugerrors.Wrap) but we don't use
these errors often enough to keep.

fix pinning

This commit adds a new set of sharness tests for pinning, and addresses
bugs that were pointed out by said tests.

test/sharness: added more pinning tests

Pinning is currently broken. See issue #1051. This commit introduces
a few more pinning tests. These are by no means exhaustive, but
definitely surface the present problems going on. I believe these
tests are correct, but not sure. Pushing them as failing so that
pinning is fixed in this PR.

make pinning and merkledag.Get take contexts

improve 'add' commands usage of pinning

FIXUP: fix 'pin lists look good'

ipfs-pin-stat simple script to help check pinning

This is a simple shell script to help check pinning.

We ought to strive towards making adding commands this easy.
The http api is great and powerful, but our setup right now
gets in the way. Perhaps we can clean up that area.

updated t0081-repo-pinning

- fixed a couple bugs with the tests
- made it a bit clearer (still a lot going on)
- the remaining tests are correct and highlight a problem with
  pinning. Namely, that recursive pinning is buggy. At least:
  towards the end of the test, $HASH_DIR4 and $HASH_FILE4 should
  be pinned indirectly, but they're not. And thus get gc-ed out.
  There may be other problems too.

cc @whyrusleeping

fix grep params for context deadline check

fix bugs in pin and pin tests

check for block local before checking recursive pin

DOCS: Updated FUSE docs

Add additional link manipulation functions

Add hamming distance calculation to bloom filters

add more bitswap task workers

changed IPFS_TASK_WORKERS to IPFS_BITSWAP_TASK_WORKERS

increase window size for yamux streams