Use quiet ttMove in qsearch() (7962287)

Idea from Daniel Jose:
http://www.talkchess.com/forum/viewtopic.php?t=54290

**STC: Hash=16**

    LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
    Total: 33067 W: 6670 L: 6571 D: 19826

**LTC: Hash=64**

    LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
    Total: 41181 W: 7008 L: 6920 D: 27253

And another one to verify no regression with hash pressure:

**STC: Hash=4**

    LLR: 2.96 (-2.94,2.94) [-4.00,0.00]
    Total: 25085 W: 5059 L: 4991 D: 15035

In the current SF code, there is a comment that claims that it would trigger qsearch explosion. Perhaps it was before QS recapture was introduced, but now I don't see how this could possibly create a qsearch explosion. If anyone has an example of such a qsearch explosion, I'm curious to see.

No functional change.