Remove public one-arg constructor magic

This pull request serves as a basis for discussion whether the feature introduced in xp-framework/rfc#243 [see below] that public one-arg constructors will be invoked for deserialization automagically should be kept or not. It covers the case for `lang.types.Number`, e.g., which could be handled separately, and removing it fails numerous tests, so **don't merge this!**.

@iigorr saw a problem with this behaviour when he used more complex transfer objects.

*The text in the RFC states:*
> When deserializing parameters from strings, the parameter type is taken into account. If the parameter type is a value object, the reflected class is checked for either a public one-arg constructor or a public static valueOf() method.