Use less time if evaluation is not worse than for previous move and even less time if in addition no fail low encountered for current iteration.

STC: 10+0.1
ELO: 5.37 +-2.9 (95%) LOS: 100.0%
Total: 20000 W: 3832 L: 3523 D: 12645

STC: 10+0.1
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 17527 W: 3334 L: 3132 D: 11061

LTC: 60+0.6
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 28233 W: 3939 L: 3725 D: 20569

LTC: 60+0.6
ELO: 2.43 +-1.4 (95%) LOS: 100.0%
Total: 60000 W: 8266 L: 7847 D: 43887

LTC: 60+0.06
LLR: 2.95 (-2.94,2.94) [-1.00,3.00]
Total: 38932 W: 5408 L: 5207 D: 28317

Resolves #547

Adjust the unsupported pawn penalty when the pawn is supporting 2 pawns
(for example g7 in f6-g7-h6)

Passed STC
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 23833 W: 4384 L: 4158 D: 15291

Passed LTC
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 42711 W: 5918 L: 5655 D: 31138

Bench: 8390233

Resolves #549

And compensate in the PSQT.

STC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 27714 W: 5161 L: 5052 D: 17501

LTC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 36354 W: 5008 L: 4909 D: 26437

Bench: 8603285

Resolves #556

60+0.6:
LLR: 2.96 (-2.94,2.94) [0.00,4.00]
Total: 102533 W: 14270 L: 13842 D: 74421

Resolves #558

No functional change

Resolves #564

STC:
LLR: 4.06 (-2.94,2.94) [0.00,5.00]
Total: 149395 W: 28029 L: 27208 D: 94158

LTC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 9628 W: 1368 L: 1217 D: 7043

bench: 8076724

Resolves #565

No functional change

Resolves #567

Time management is really too complex, our aim is
to simplify it, but for time being at least rewrite
in an understandable way.

No functional change.

No functional change

Resolves #570

This flag is functionally identical to '-std=c++11' flag which
is part of standard flags.

No functional change

Resolves #571

Verified that is improvement with multiple threads:

LLR: 2.95 (-2.94,2.94) [0.00,4.00] sprt @ 30+0.3 th 3
Total: 14817 W: 2103 L: 1915 D: 10799

LLR: 2.96 (-2.94,2.94) [0.00,4.00] sprt @ 15+0.15 th 7
Total: 10264 W: 1498 L: 1321 D: 7445

Verified that is not a significant regression with a single thread:

LLR: 2.96 (-2.94,2.94) [-4.00,0.00] sprt @ 60+0.6 th 1
Total: 23975 W: 3294 L: 3210 D: 17471

Resolves #575

There is no reason to compile 3 different copies of search(). PV nodes are on
the cold path, and PvNode is a template parameter, so there is no cost in
computing:

const bool RootNode = PvNode && (ss-1)->ply == 0;

And this simplifies code a tiny bit as well.

Speed impact is negligible on my machine (i7-3770k, linux 4.2, gcc 5.2):

            nps   +/-
test    2378605  3118
master  2383128  2793
diff      -4523  2746

Bench: 7751425

No functional change.

Resolves #568

Almost no functional change. Bench is unchanged.

Resolves #230
Resolves #573

STC:
LLR: 2.95 (-2.94,2.94) [0.00,5.00] sprt @ 5+0.1 th 21
Total: 7068 W: 1121 L: 975 D: 4972

LTC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00] sprt @ 12+0.12 th 21
Total: 26691 W: 3594 L: 3481 D: 19616

No functional change with a single thread

Resolves #574

10+0.1:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 41963 W: 7967 L: 7883 D: 26113

60+0.6:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 132314 W: 17939 L: 17969 D: 96406

Resolves #580