Update copyright year

No functional change.
Scale eval when down to only one pawn

Passed both short TC
LLR: 2.97 (-2.94,2.94) [-1.50,4.50]
Total: 11921 W: 2346 L: 2208 D: 7367

And long TC
LLR: 2.97 (-2.94,2.94) [0.00,6.00]
Total: 21002 W: 3395 L: 3197 D: 14410

bench: 7602383
Ensure move_importance() is non-zero

In case ply is very high, function will round
to zero (although mathematically it is always
bigger than zero). On my system this happens at
movenumber 6661.

Although 6661 moves in a game is, of course,
probably impossible, for safety and to be locally
consistent makes sense to ensure returned value
is positive.

Non functional change.
Remove duplicated code

Introduce update_stats() and remove correspondng
duplicated code.

No functional change.
Fix a typo

Spotted by Isaac H. Dunn.

No functional change.
Tweak King PST tables

First tested with 50K games at very short TC of 5+0.05
ELO: 3.11 +-2.0 (95%) LOS: 99.9%
Total: 49665 W: 10941 L: 10497 D: 28227

Then retested with usual SPRT at short TC
LLR: 2.96 (-2.94,2.94) [-1.50,4.50]
Total: 16875 W: 3198 L: 3049 D: 10628

And at long TC
LLR: 2.95 (-2.94,2.94) [0.00,6.00]
Total: 5890 W: 985 L: 857 D: 4048

bench: 7800379
Assorted grammar fixes

Mainly from Lyudmil Antonov and
one from Henri Wiechers and Louis Zulli.

No functional change.
Zero out pawn PSQT
Zero out knight PSQT
Zero out bishop PSQT
Zero out rook PSQT
Zero out queen PSQT
Zero out king PSQT
Merge branch 'psqt' of github.com:dorzechowski/Stockfish into psqt

Conflicts:
	src/psqtab.h