Rename internal enumerable state to :members

Enumerable#entries is defined by ruby itself. Overwriting it can lead
to weird consequences if the overwritten name does not resolve to an
array.
Nuke useless visibility constraint

alias_method respects visibility anyways.
Resolve the collection presenter class asap
Perform #public_send in Presenter#method_missing
Use idiomatic param names in Presenter
Make Undefined a new frozen Module instance