Add ItemArray
Let Nanoc::Site use Nanoc::ItemArray
Only use item array cache when frozen
Fix typo in item array example
Clean up DELEGATED_METHODS
Add tests for slice/[] with ranges
Fix freezing
Add frozen ItemArray#collect! test case
Limit #keep_if and #select! test cases to 1.9.x
Fix frozen assertions in ItemArray
Clean up frozen assertions
Merge pull request #217 from ddfreyne/feature-find-item-by-identifier

Find item by identifier