Review QL.require and QL.ensure messages

[Richard Gomes]

I've added some more methods in class QL which allow more flexibility to validations without incurring on performance penalties.

In a nutshell, you can pass a format string and a variable list of arguments to QL.require and QL.ensure. The message will only be built when the condition fails.

This task is about a complete code review, intending to rewrite error messages which where simplified or had useful information suppressed. There are several other messages which are being composed during the call when they should't, due to performance reasons.

Because reviewing all QL.require and QL.ensure by hand is not practical, we should think about tools or shortcuts which lead us to identify those calls which really need review. At this point, it's not determined how we could speed up this very boring task.

This is an example:

QuantLib/C++:
        QL_REQUIRE(n >= Interpolator::requiredPoints,
                   "not enough instruments: " << n << " provided, " <<
                   Interpolator::requiredPoints << " required");

JQuantLib/Java:
        QL.require(n >= ts.interpolator().requiredPoints(),
                "not enough instruments: %d provided, %d required",
                n, ts.interpolator().requiredPoints());