Ruby bindings RFE: Implement iteration through Ruby's Enumerable module.

[jackorp]

Iterating over collections (e.g. ReldepList, PackageQuery, ...) in Ruby currently requires a quite unwieldy while loop.
To get elements out of PackageQuery for example:

item = collection.begin
c_end = collection.end

while item != c_end
  puts item.value.get_name
  item = item.next
end

In idiomatic ruby, the methods from Enumerable module are preferred. The mentioned loop should look like:

collection.each do |item|
  puts item.get_name
end

For any iterable collection, there are 2 requirements are needed to make use of the enumerable module:

1. including Enumerable module in the class to get the methods
2. implement instance method each that iterates over each element, yielding it in a block.

After just these 2 steps we also acquire other methods such as #map, #find, #select, #inject, etc... from Enumerable.