I have been working hard on the next release of outlet. Since a lot of
the changes I was making were sort of experimental, I created a branch
to work on them: the 'many-to-many' branch.

The main features are:
* One-to-one and many-to-many relationships
* PHP-5.2's DateTime support
* Fluent-interface query API
* Eager fetching

The code currently passes the unit tests, but I feel it still needs some
polish.

There is one BC-incompatible change that was necessary to implement
many-to-many relationships without creating a linking entity in code:
Collections.

On this new version, relationship methods that currently return an array
of entities will now return a Collection object. This object implements
extends ArrayObject so it can be used in most situations where an array
can be used. Here is an example:

<?php

// entities should now be defined like this
class Project {
  private $bugs;
  ...
  public function getBugs () {
    return $this->bugs;
  }
  public function setBugs(Collection $bugs) {
    $this->bugs = $bugs;
  }
  ...

...

$bugs = $project->getBugs();

// bugs is an instance of Collection
// but it behaves just like an array

// you can call count it
echo count($bugs);

// and you can use it in a foreach
foreach ($bugs as $bug) {
  echo $bug->Description;

// you no longer need an addBug method
$project->getBugs()->add($bug);

// bug if you create it, you can still use it just the same
$project->addBug( $bug );

?>

Everything else works the same.

I would really appreciate any feedback on these changes, so if you're
adventurous, please check it out:

svn://knowledgehead.com/outlet/branches/many-to-many