Simplify a condition in is_KXK()

No functional change.
Small renaming in material weights

Also dropped some temporary variable: compiler
is more than able to push on stack temp values
by itself (verified).

No functional change.
Move game_phase() to Position

It seems a more natural to place this
function there.

No functional change.
Better value clipping in game_phase()

No functional change.
Add AUTHORS
Remove some duplicates
Ensure ttValue != VALUE_NONE in singular extension search

The assert:

  assert(ttValue != VALUE_NONE);

Could fire for multiple reasons (although is very rare),
for instance after an IID we can have ttMove != MOVE_NONE
while ttValue is still set at VALUE_NONE.

But not only this, actually SMP is a source of corrupted
ttValue and anyhow we can detect the condition:

 ttMove != MOVE_NONE && ttValue == VALUE_NONE

even north of IID.

Reported by Ronald de Man.

It is so rare that bench didn't change.

bench: 7710548
Some reformatting in pawns.cpp

No functional change.
Merge pull request #5 from glinscott/authors

Add AUTHORS
Scale down endgames with pawns on one or two adjacent files
Original version of shane's patch
Revert "Check for an available slave early on"

This reverts commit ce1c260ea97c14eea996d0a2638f4876ccbc412b.
Merge pull request #8 from glinscott/revert_ce1c260

Revert "Check for an available slave early on"
A bit more cleanup
Merge pull request #9 from glinscott/pawnspan

Scale down endgames with pawns on one or two adjacent files

Passed STC
LLR: 2.95 (-2.94,2.94) [-1.50,4.50]
Total: 16081 W: 2745 L: 2604 D: 10732

Passed LTC
LLR: 2.95 (-2.94,2.94) [1.00,6.00]
Total: 123832 W: 17292 L: 16584 D: 89956

128k games to measure ELO at 15+0.05:
ELO: 2.07 +-1.1 (95%) LOS: 100.0%
Total: 128000 W: 21632 L: 20869 D: 85499

New bench: 8028792
Pack 3 TT entries in 32 bytes cluster

Idea from Ron Britvich

Code reworked by Marco Costalba and Joona Kiiski

Bench: 8095369

Resolves #3
Resolves #10
Change the install prefix for Haiku

* /boot/common was removed from Haiku
* The equivalent path now that package management has been implemented is /boot/system/non-packaged

No functional change

Bench: 8759681
Fix Singular extension condition to handle mate scores

With Eelco's patch "Don't special case for abs(beta) >= VALUE_MATE_IN_MAX_PLY" condition "abs(ttValue) < VALUE_KNOWN_WIN" has been removed from singular extension search, and condition "abs(beta) < VALUE_KNOWN_WIN" was added to the SingularExtensionNode definition.
This might lead to problems, especially in positions, where a mate is due.
For example, this position 5rk1/4K1pp/8/5PPP/8/8/8/1R6 w - - 12 1 triggers an assert.
stockfish: search.cpp:434: Value {anonymous}::search(Position&, Search::Stack*, Value, Value, Depth, bool) [with {anonymous}::NodeType NT = (<unnamed>::NodeType)2u; bool SpNode = false]: Assertion `-VALUE_INFINITE <= alpha && alpha < beta && beta <= VALUE_INFINITE' failed.

So let's re-insert the removed condition.
First spotted by Uri Blass, fix by me.

Bench: 8759675
Add bonuses for Minors attacking enemy pieces(except pawns) even when they are protected by enemy pawns.

Patch passed STC
LLR: 2.95 (-2.94,2.94) [-1.50,4.50]
Total: 8206 W: 1426 L: 1304 D: 5476

and LTC
LLR: 2.97 (-2.94,2.94) [0.00,6.00]
Total: 19534 W: 2821 L: 2640 D: 14073

Bench: 9942172