Previously `Iter` was meant to be a collection iterator class, but now
we need a more generalized notion of iterator, so we move some
collection-specific methods out and designate `Iter` a general iterator
class, while `CollectionIterator` takes its former place.
`APlayer` and `ATrader` represented player and trader (`ShopVolume`)
with a single object instance. Such design, if used for all actors,
could have led to mutitute of problems rooted in need to find that
single object for any given native actor: we'd need to store
object-actor pairs separately and look through pairs lists, which is
hardly a sane design.
Now Acedia switches to a different design, where a single in-game entity
(i.e. actor) can have several interfaces referring to it. All equaly
valid. Refactoring `APlayer` and `ATrader` into `EPlayer` and `ETrader`
is a first step in that direction.
Anton Tarasenko