Small code style reformatting

No functional change.
Fix a warning with MSVC 2010

Warning C4267: 'argument' : conversion from 'size_t' to 'int', possible loss of data

No functional change.
Document Threat[] indices
From Marco's repo.

No functional change.
Correct bench timing

No functional change.
Ensure printing UCI info in multi-pv case

After commit 94b1bbb68be6b0bc3aaf1cb804841a022bcc7007, in case available root moves are less than multiPV, we
could never reach condition:

PVIdx + 1 == multiPV

and as a consequence UCI output is not printed.

Fixed suggested by Joerg Oster.

No functional change.