Applied polar decomposition patch. Fixes Issue 621. Thanks to Christian for the report, Joshua for the fix, Dongsoo for checking the fix.

Applied picking cloth patch. Fixes Issue 646. Thanks to Dongsoo.
Applied patch Softbody updateConstraints. Fixes Issue 503. Thanks to Dave Bruce Phillips and Dongsoo.
Fix various warnigns under Mac OSX.

UnitTests/BulletUnitTests/btCholeskyDecomposition.cpp

@@ -0,0 +1,40 @@
+#include "btCholeskyDecomposition.h"
+
+int choleskyDecompose(const btMatrix3x3& A, btMatrix3x3& L)
+{
+  // TODO Check that the A matrix is symmetric
+
+  // Iterate over the elements of the upper triangle of A
+  for (unsigned int i = 0; i < 3; ++i)
+  {
+    for (unsigned int j = i; j < 3; ++j)
+    {
+      btScalar sum = A[i][j];
+      for (unsigned int k = 0; k < i; ++k)
+      {
+        sum -= L[i][k] * L[j][k];
+      }
+
+      if (i != j)
+      {
+        L[j][i] = sum / L[i][i];
+      }
+      else
+      {
+        if (sum <= btScalar(0))
+        {
+          return btCholeskyDecomposition::FAILURE_POSITIVE_DEFINITE;
+        }
+
+        L[i][i] = sqrt(sum);
+      }
+    }
+  }
+
+  L[0][1] = btScalar(0);
+  L[0][2] = btScalar(0);
+  L[1][2] = btScalar(0);
+
+  return btCholeskyDecomposition::SUCCESS;
+}
+