Added and implemented TimberPostsIterator and TimberQueryIterator
Make sure also Timber::get_post works with the iterators
Fix Timber::get_pid (I don't think this one worked before either..)
Remove next() implementation in TimberQueryIterator
Don't create yet another object if given object is already of the right type
Let the unit test use the result of Timber::get_posts as an Iterator instead of as an array
Create TimberPostsCollection object that uses TimberPostsIterator to push the current post as the current global $post
Implemented get_posts on TimberQueryIterator, that either returns the plain TimberPosts array, or the TimberPostsCollection
Split up Timber::query_posts and Timber::get_posts.
Use the passed in PostClass in Timber::handle_post_results
Fix Timber::get_post to use an ArrayObject instead of an Iterator
Restore unit test from 4ba7c09 now that get_posts returns an array
Implement getting posts from slug with hash and post type
Added basic test for TimberQueryIterator

TimberIteratorTest::testTheLoop simply shows how a template tag like 'get_the_title' can now be used in a template file. In the test, replace 'Timber::query_posts' by 'Timber::get_posts' to get an array (like the old behaviour) and see the test fail.
Update timber-menu.php

set $this->has_child_class to true to prevent the class from being added multiple times (was added once per child item)
Add alt property to TimberImage
Add test for TimberImage->alt property
Add missing title as alt text test
Update travis.yml to test against WP 3.8.1
Revert back to WP 3.5.1 in travis