Convert from formulas to tables in passed pawns

Allows an easier tuning of this very important
part of evaluation. Also make it easier to
further expand the logic without messing up
the code.

I think that this patch, that was really no trivial to
implement (it took me many attempts to get it right) paves
the way to further functional changes both by SPSA tuning
and by better logic or even try some simplification (that
would be very good!): now it is much easier to work in this
part of code and I think developers will be glad, so
please apply.

No functional change.
Is that supposed to make the code easier to understand?