Simplify idle_loop()

No functional change
Small tweak to idle_loop()

In case of a succesful late join we set again
'searching' flag, so we can restart search
immediately without an useless lock/unlock
cycle.

No functional change.
Simplify Time Management UCI options

No functional change
Retire struct Log

No more used now that we have removed
"Write Search Log" UCI option.

No functional change.
Rename "Contempt Factor" to "Contempt"

Suggested by Ronald and Lucas on talkchess.

No functional change.

Conflicts:
	src/ucioption.cpp
King-pawn threat bonus for endgames.

STC:
LLR: 2.95 (-2.94,2.94) [-1.50,4.50]
Total: 10224 W: 1765 L: 1638 D: 6821

LTC:
LLR: 2.96 (-2.94,2.94) [0.00,6.00]
Total: 6923 W: 1027 L: 899 D: 4997

bench 7818100

Resolves #49
Rename time variable to reflect UCI parameters

On top of previous patch, rename time variables to
reflect the simplification of UCI parameters.

It is more correct to use as varibales directly the
corresponding UCI option, without intorducing redundant
intermediate variables.

This allows also to simplify the code.

No functional change.
Rearrange evaluation constants definitions

Make them more uniform and consistent.

No functional change.

Conflicts:
	src/evaluate.cpp
Fix spacing.

No functional change.
Evaluate king safety when no queen is present.

LLR: 2.97 (-2.94,2.94) [-1.50,4.50]
Total: 16657 W: 3547 L: 3391 D: 9719

LLR: 2.95 (-2.94,2.94) [0.00,6.00]
Total: 31258 W: 5664 L: 5403 D: 20191

Bench: 8331165

Resolves #51
Change history reduction in LMR to be a full ply.

STC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 9829 W: 2142 L: 1998 D: 5689

LTC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 27162 W: 4802 L: 4692 D: 17668

Bench: 7284120

Resolves #53
Cap evaluation based null move extra reduction to three plies

It's a zero elo patch, and a reasonable safeguard against uncontrolled extreme reductions.

STC:
ELO: -0.08 +-2.0 (95%) LOS: 46.9%
Total: 40000 W: 6728 L: 6737 D: 26535

LTC:
ELO: -0.14 +-1.8 (95%) LOS: 44.0%
Total: 40000 W: 5557 L: 5573 D: 28870

Bench: 7201830
Remove use of half-ply reductions from LMR, Null-move, IID and
Singular extensions.

STC:
ELO: 3.80 +-3.1 (95%) LOS: 99.2%
Total: 19727 W: 4190 L: 3974 D: 11563

LTC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 7647 W: 1356 L: 1214 D: 5077

Bench: 6545733

Resolves #55
Clean up VALUE_KNOWN_WIN conditions

A patch (+ some extra changes) passed with:

STC
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 14575 W: 3101 L: 2967 D: 8507

LTC
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 42579 W: 7580 L: 7496 D: 27503

Bench: 6545733

Resolves #52
Move ONE_PLY to be 1 instead of 2: search()

Now that half-plies are no more used we can simplify
the code assuming that ONE_PLY is 1 and no more 2.

Verified with a SMP test:
LLR: 2.95 (-2.94,2.94) [-4.50,0.00]
Total: 8926 W: 1712 L: 1607 D: 5607

No functional change.
Trivial code style fixes

Mainly to sync mine and official repo.

No functional change.
Convert TT depth to int8_t

Now that half plies have been removed from the engine, we can encode
TT depth into an int8_t.

Range is -128 to +127, so it goes still further than the previous
limit of 121 plies (with ONE_PLY == 2 where depth - DEPTH_NONE was
encoded as an uint8_t).

No functional change.

Resolved #60
Speculative prefetch

Idea by Peter Oesterlund.
Implemented and tested by Joerg Oester

STC 3 threads
ELO: 3.19 +-2.1 (95%) LOS: 99.9%
Total: 40000 W: 7576 L: 7209 D: 25215

LTC
LLR: 2.96 (-2.94,2.94) [0.00,6.00]
Total: 22026 W: 3829 L: 3619 D: 14578

STC
LLR: 2.95 (-2.94,2.94) [-1.50,4.50]
Total: 7291 W: 1531 L: 1404 D: 4356

No functional change

Resolves #61
Extend King Threats to all pieces (other than pawns).

STC
LLR: 2.99 (-2.94,2.94) [-1.50,4.50]
Total: 20559 W: 4261 L: 4095 D: 12203

LTC
LLR: 2.96 (-2.94,2.94) [0.00,4.00]
Total: 75232 W: 13097 L: 12696 D: 49439

Bench: 7543790

Resolves #63
Reformat and rename hash_after_move()

Align to standard coding style and properly use
enum types. Rename while there.

No functional change.