More uniform tracing code

No functional change.
Re-add "Pawn Structure" UCI option

And reshuffle the code to not special case
this parameter.

No functional change.
Add Pawn Structure also to polyglot.ini

No functional change.
Shrink engine UCI name

Some GUI have problems with long names.

Reported by George Speight.

No functional change.
Merge branch 'master' into phash