An iterator for AList

[valdisz]

The forlist macro comes from when there were no iterators. AList is a custom container that needs to be replaced with std containers, but the amount of work is immense. Therefore I have added iterator interface (begin and end) methods so that modern for (var item : iterator) syntax can be used in the code. It will allow the removal of the forlist macro from the codebase over time.

New API

AList::begin - iterator for the beginning of the list
AList::end - iterator for the end of the list
AList::iter<T> - allows for strongly typed iteration over the AList

Improvements

1. Will allow the use of modern C++ for loop syntax.
2. All iterator-based APIs from std namespace will work on AList instances.

[jt-traub]

This is good. It at least makes the code cleaner in the interim until we can actually get around to removing AList.