Truffle-DSL: API cleanup.

[Christian Humer]

Hey folks,

I am considering a few removals from the Truffle-DSL API package
truffle.api.dsl.

Annotation - Reason
@NodeContainer - Enables minor code sugar for declaring multiple operations
within one class but introduces a lot of complexity.
@NodeId - Only required to disambiguate some cases in classes with
@NodeContainer.
@SpecializationListener - Same as putting some code in the copy constructor
of the node.

As far as I know these annotations are barely ever used. However if you are
using it, please let me know so I can work out a migration strategy for you.


- Christian Humer