Revert "Use a per-thread array"

This reverts commit 800410eef1 and instead increases
stack size.

I went through the old emails with Daylen that reported the
crash issue on Mac OS X and was fixed by 0049d3f337.

It was reported default stack size for a thread in Mac OS X is 8
megabytes while the patch that we are reverting allows to reduce
stack size at max of about 217KB, so the reason for the crash was
only marginal in MAX_MOVES value. On those emails Daylen also
hinted how to increase stack size for Mac OS X to 16MB.

So prefer to increase stack size to 16MB instad of re-inventing
the wheel and do our home grown stack as we did with the patch
that we are now reverting (it will remain anyhow in git history
for documentation purposes).

No functional change.

src/thread.cpp

@@ -83,11 +83,10 @@ void ThreadBase::wait_for(volatile const bool& b) {
 Thread::Thread() /* : splitPoints() */ { // Value-initialization bug in MSVC
 
   searching = false;
-  maxPly = splitPointsSize = curPage = 0;
+  maxPly = splitPointsSize = 0;
   activeSplitPoint = NULL;
   activePosition = NULL;
   idx = Threads.size();
-  movePages.resize(MAX_PLY_PLUS_6 * MAX_MOVES);
 }