Fixed warnings in Bullet/src core library

Thanks Martijn Reuvers from Two Tribes B.V. (www.twotribes.com) for the patch

To make this work more visible, suppress warnings in external libraries in Extras (COLLADA_DOM, libxml and glui contain many warnings)
Added PreprocessorDefinitions: _CRT_SECURE_NO_DEPRECATE;_CRT_NONSTDC_NO_DEPRECATE to vcproj files

src/BulletCollision/BroadphaseCollision/btDbvt.cpp

@@ -279,7 +279,7 @@ static btDbvt::Node*			topdown(btDbvt* pdbvt,
 			{
 				if((splitcount[i][0]>0)&&(splitcount[i][1]>0))
 				{
-					const int	midp=btFabs(splitcount[i][0]-splitcount[i][1]);
+					const int	midp=static_cast<int>(btFabs(static_cast<btScalar>(splitcount[i][0]-splitcount[i][1])));
 					if(midp<bestmidp)
 					{
 						bestaxis=i;