Allow a class prefix to be specified when calling Doctrine_Core::loadModels()

Doctrine allows you to generate class names such as Blog_Model_Post in Post.php, but Doctrine::loadModels() is not able to load these models conservatively, as the class name and file name differ.

I suggest adding a third parameter to Doctrine_Core::loadModels() to specify a class prefix, for example:

Doctrine_Core::loadModels('/modules/blog/models', Doctrine_Core::MODEL_LOADING_CONSERVATIVE, 'Blog_Model_');

Code changes (I think) would be something like this:

public static function loadModels($directory, $modelLoading = null, $classPrefix = null)
{
...
	$className = $e[0];
	
	if ($classPrefix) {
		$className = $classPrefix . $className;
	}
...
}

Since the argument is optional, this change shouldn't break any existing code.

NB: This is not PEAR-style file/class naming.