add support for file notifications with filters
hash counter rebalance API
Rebalance support:
- job and lockage semantics
- live block relocation
- block hold flag
- file relocation (via snapshot + copy + removal)
- rebalanced flag and cleanup
introduce 'node is gone' logic
node removed from the cluster withh return 410 - Gone
- http 410 is marked retriable in the client
- http 410 is equivalent to 200 in jobs that might target removed nodes
syncronize end of rebalance
sxsetup: don't call --mod if the cluster is being rebalanced (work-around for bb#660)
Also call --info right before --mod to close a possible race
Introduce single block download fallback to multi_download.

single_download() function downloads blocks sequentially in case of
multi_download() fails.
Fix fast remote to remote copy (bb#702)
minor fixes
Clear error between retries when got 429 response (bb#705)
let "sxadm cluster -M" save the updated configuration
increase file delete job timeout

similar to file flush job timeout, based on no of blocks and nodes
fix memleak when using input streams
minor sxvol-related usability improvements (bb#560)
always reset qm_list queries
Rework r2rfast (bb#710)

Take dest hosts from different tempfile. This is the same file that was used for getting download hosts. Now only use stored tempfile offsets.

Fix some error paths to not leak.
better error msg (bb#492)
limit logger msgs for node --info (bb#511)
fix typo
sxcp progress cosmetics

Prevent progress bar flashing when doing transfer retries or blocks are
skipped.