This reverts commit f3fba53e.

This was deprecated and unused for a long time,
decision to not log queries was made.

Resulting in max ~ 4000 q/s.

Updated documentation and corrected default settings.

The idea is to insert colliding items in the H distance of
the original hash value. H must be chosen to accomodate log(N)
items, we use sizeof(unsigned). Unlike in linear probing,
lookup is always in constant time and doesn't require
extra memory and chaining costs as in external chaining.
Extra memory is just sizeof(unsigned) per bucket.
Builtin __builtin_ctz() is used for fast hop lookup.

Herlihy, Maurice and Shavit, Nir and Tzafrir, Moran (2008).
"Hopscotch Hashing". DISC '08: Proceedings of the 22nd
international symposium on Distributed Computing.
Arcachon, France: Springer-Verlag. pp. 350--364.
http://people.csail.mit.edu/shanir/publications/disc2008_submission_98.pdf

Change-Id: I414a84fd02871bf78445009a82adfd2e355d67ce

Change-Id: I77615a328dce98e39964c567b55cf7c4dca331e2

Prints zone status in following format:
<name> | type={master,slave} | serial=N | <state>

Configuration can still be overriden using the command
line parameters.

refs #2136

refs #2136

Doesn't guarantee waking up of the Idle threads
and blocks when used in dt_start().
Caller should either activate existing threads or
use dt_start() instead.

refs #1441