Feature/bridge from onebuilder to manybuilder

[DyegoMaas]

Improved navigation between different interfaces. Now it is possible to link builders in all directions, like:

MagicFactory.For<Person>()
    .Many(10).With(x => x.Age = 5)
    .PlusOne().With(x => x.Age = 10)
    .Plus(10).With(x => x.Age = 15)

Also, I've made a great refactoring, and now the shared context between builders is more explicit in the implementation. It contains the default transformations and constructors used by all builders in a linked context.

The unit tests were also reestructured, being a lot more explicit in many aspects of the implementations.