Fix issues detected by Coverity Scan

Most of Coverity Scan reports are false
positives, but in rare cases we have
confirmed (very small) issues.

No functional change.
Speed up by almost 3%

This apparentely silly tweak allows
to speed up the bench by almost 3%.

Not clear why, repeating with perft,
the speed up vanishes.

Suggested by Jonathan Calovski.

No functional change.
Move game phase constants to enum Value

No functional change.
Reformatting in material.h

No functional change.
Remove rook passers eval completely

Tested in no-regression mode.

Passed STC
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 17727 W: 3248 L: 3122 D: 11357

And (a very long!) LTC
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 106327 W: 16258 L: 16265 D: 73804

bench: 7396783
We can add an integer to a Value

We have defined corresponding operators,
so rely on them to streamline the code
and increase readibility.

No functional change.
Remove some useless casts

No functional change.
Fix Intel compiler warnings

Fallout from previous patch: Intel compiler
is very noisy.

No functional change.