Make operator<< to return void

This should help preventing misuse.

No functional change.
Queen vs. 3 pieces imbalance

Passed both STC
LLR: 7.32 (-2.94,2.94) [-1.50,4.50]
Total: 98108 W: 18087 L: 17576 D: 62445

And LTC
LLR: 2.95 (-2.94,2.94) [0.00,6.00]
Total: 15082 W: 2417 L: 2248 D: 10417

bench: 7717336
Update Readme to 128 max threads

No functional change.
Speed up apply_weight

Speed up by about 2% this hot path function pre-calculating
midgame and endgame values of the weight.

No functional change.
Remove QueenOn7th and QueenOnPawn

Small simplification.

Passed SPRT(-3,1) both at STC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 17051 W: 3132 L: 3005 D: 10914

and LTC:
LLR: 4.55 (-2.94,2.94) [-3.00,1.00]
Total: 24890 W: 3842 L: 3646 D: 17402

The rationale behind this is that I've never managed to add a
Queen on 7th rank bonus in DiscoCheck, because it never showed
to be positive (evne slightly) in testing. The only thing that
worked is Rook on 7th rank.

In terms of SF code, it seemed natural to group it with QueenOnPawn
as well as those are done together. I know you're against groupping
in general, but when it comes to non regression test, you are being
more conservative by groupping. If the group passes SPRT(-3,1) it's
safer to commit, than test every component in SPRT(-3,1) and end up
with the risk of commiting several -1 elo regression instead of just
one -1 elo regression.

In chess terms, perhaps it's just easier to manouver a Queen (which
can more also diagonaly) than a Rook. Therefore you can let the search
do its job without needing eval ad-hoc terms to guide it. For the Rook
which takes more moves to manouver such eval terms can be (marginally)
useful.

bench: 7473314
Smaller and faster profile-build binaries

I have noticed that increasing the bench depth produces
progressively smaller and slightly faster executables at
the cost of longer compile times.  Also using bench "time"
instead of "depth" seems to produce slightly smaller/faster
executables  given comparable compile times.

I have made a new Makefile that generates smaller and
about 1% to 2% faster profile executables at only a
little extra compile time.  On  my mobile 2GHz i7 a
full profile build time goes from 3'48" to 4'13" and
the exe goes down by 5% from 416,310 bytes to 395,567
bytes.

No functional change.
Small tidy up in move_to_san

No functional change.