the engine is finally in the strongest state it’s ever been! (i think)

for those who have not been obsessively following this project, the
search part of the engine has gone through two rewrites now. i kept
hitting walls where i really shouldn’t have; improvements that should
have been huge gains did a lot less than expected. i did the rewrites in
an attempt to find a potential bug that would kill future attempts at
improvements, but i never really found anything significant.

i never really got the engine to it’s pre-rewrites strength until now.
read it and weep (~17 elo gain)

--------------------------------------------------
Results of trout-exe-max vs trout-exe-asp-tweak (8+0.08, NULL, 
16.000000MB, UHO_Lichess_4852_v1.epd):
Elo: -16.96 +/- 14.18, nElo: -22.54 +/- 18.80
LOS: 0.94 %, DrawRatio: 33.99 %, PairsRatio: 0.82
Games: 1312, Wins: 380, Losses: 444, Draws: 488, Points: 624.0 (47.56 %)
Ptnml(0-2): [63, 175, 223, 153, 42], WL/DD Ratio: 1.79
LLR: -2.98 (-101.3%) (-2.94, 2.94) [0.00, 10.00]
--------------------------------------------------

it’s still not super great because elo improvements are coming slooowww
and we’re still only 17 elo up with many more features than before. it’s
still nice, though.

implemented since last devlog:

• “improving” heuristic (13 elo): a position is said to be “improving” if the static evaluation now is higher than the one from a move ago. we can use this to tweak some parameters in the search, like when to cut off for LMP, which is what i did. need more testing for the other features.
• lmr limit (16 elo): my LMR implementation was slightly bugged and would reduce too many moves; normally the first couple are spared, but i had every move except the first reduced.
• negative captures below quiet moves (13 elo): for some reason, i had captures that were deemed negative by SEE (bad captures, basically - trading a queen for a pawn would be one) sorted above all quiet moves. i moved them to the bottom of move sorting.
• redo aspiration windows (36 elo): i redid the implementation for aspiration windows slightly. it should be smarter about bounds now. that makes around 100 elo for aspiration windows cumulatively now, which is kinda crazy

here’s a picture of htop when i was running the engines against each othe for elo testing. i thought it was kinda funny