We need parens so that operators are evaluated in the right order.

This adds extra params around a bunch of things. I'll let the gods of Depot
sort that out.

BTW: Arithmetic.Div is still totally broken. It somehow booches the prepared
statement. I tried changing the operator String to "//" and that sorta worked,
but then the next operator over was missing...
I'm working around this using Mul, but it'd be nice..

src/java/com/samskivert/jdbc/depot/BuildVisitor.java

@@ -188,9 +188,11 @@ public abstract class BuildVisitor implements ExpressionVisitor
     public void visit (BinaryOperator binaryOperator)
         throws Exception
     {
+        _builder.append('(');
         binaryOperator.getLeftHandSide().accept(this);
         _builder.append(binaryOperator.operator());
         binaryOperator.getRightHandSide().accept(this);
+        _builder.append(')');
     }
 
     public void visit (IsNull isNull)