IgnoreCase, Seconds and Minutes can be used on numerical constraints

[OsirisTerje]

Currently the following is allowed by the compiler, thought it is warned by the NUnit.Analyzer:

   Assert.That(42,Is.EqualTo(42).IgnoreCase  // Raises NUnit2008 warning.   IgnoreWhitespace
   Assert.That(42,Is.EqualTo(42).IgnoreWhiteSpace);
   Assert.That(42,Is.EqualTo(42).Minutes  // Seconds also allowed.  Doesn't raise any Analyzer warnings.

The compiler should report these as errors.