Bunch of 3 small patches

This patch is the sum of:

- Grainsize of 4 instead of 8

- Removing "depth < DEPTH_ZERO"

- Change DEPTH_QS_RECAPTURES = -5 to -7

All the patches individually failed to pass SPRT but scored
around 50%.

Together they pass easily short TC:
LLR: 2.96 (-2.94,2.94)
Total: 4429 W: 964 L: 844 D: 2621

And with some difficult long TC of 60+0.05:
LLR: 2.95 (-2.94,2.94)
Total: 64133 W: 11968 L: 11532 D: 40633

bench: 4821467

src/types.h

@@ -213,7 +213,7 @@ enum Depth {
   DEPTH_ZERO          =  0 * ONE_PLY,
   DEPTH_QS_CHECKS     = -1 * ONE_PLY,
   DEPTH_QS_NO_CHECKS  = -2 * ONE_PLY,
-  DEPTH_QS_RECAPTURES = -5 * ONE_PLY,
+  DEPTH_QS_RECAPTURES = -7 * ONE_PLY,
 
   DEPTH_NONE = -127 * ONE_PLY
 };