Move Tempo to evaluation

No functional change.
Avoid to use nullChild

Should be a non functional change, but
for some reason bench is changed.

bench: 8454456
Temporary revert previous patch

Split previous patch in 2 steps: first remove
the MOVE_NULL hack, then retire nullChild.

The first step is a prerequisite
for second one and affects bench.

The second step (next patch) just removes nullChild
without affecting bench.

bench: 8205159
Remove 'update gains' hack

Use (move != MOVE_NONE) condition to
filtering out updating gains at root.

bench: 8454456
Avoid to use nullChild

Use instead:

(ss-1)->currentMove == MOVE_NULL

No functional change.
Use unsigned char as argument of std::isspace

Although signature allows an int:

int isspace( int ch );

The behavior is undefined if the value of ch is
not representable as unsigned char and is not
equal to EOF.

See

http://en.cppreference.com/w/cpp/string/byte/isspace
http://www.greenend.org.uk/rjk/tech/cfu.html

This is really a tricky corner case of C standard!

Spotted and reported by Ron Britvich.

No functional change.
Check for an available slave early on

Don't take the split lock if we don't have
available slaves (about 30-40% of times).

This new condition allows to retire the now
redundant one on number of threads.

No functional change.
Small renaming in Tracing

No functional change.
Add bonus for advanced lever

Passed both STC
LLR: 2.95 (-2.94,2.94) [-1.50,4.50]
Total: 15413 W: 2670 L: 2530 D: 10213

And LTC:
LLR: 2.95 (-2.94,2.94) [1.00,6.00]
Total: 66908 W: 9398 L: 8960 D: 48550

Bench : 7859385
Tweak outpost name

This name is more accurate, since that function evaluates only one
outpost in every call.
No functional change.
Simplify pawn threats and merge into ThreatenedByPawn[]

Tested in no-regression mode,

passed STC
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 14477 W: 2493 L: 2362 D: 9622

and LTC
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 51964 W: 7091 L: 7013 D: 37860

bench: 7875814