Enlightenment Foundation Library providing optimized data types

 Eina is a multi-platform library that provides optimized data types and a few
 tools. It supports the following data types:
  - Array
  - Hash Table
  - Double-linked list
  - Red-black tree
  - Shared string
  - Access Content types
    + Accessor: can access items of a container randomly
    + Iterator: can access items of a container sequentially