Bug when conditions are applied to more than one table

Hello all of you who develop Respect. First, let me thank you and say you're doing a really good job! I'm using Respect in a project of mine and today I was not able to perform a query based on the examples in your documentation.

The project I'm working on is a CMS, and I want to fetch all the contents that belongs to the category of ID equal to 30, which ID is different from 60. According to your documentation, I thought of this command:

$aContent = $mapper->content(array('id !=' => 60))->category[30]->fetchAll();

It was not bringing me the contents I expected, so I dove into the code and inserted an echo where you generate the query to see what the framework was looking for (release 0.5.1, file Mapper.php, line 223):

    protected function createStatement(
        Collection $collection, $withExtra = null
    ) {
        $query = $this->generateQuery($collection);

        if ($withExtra instanceof Sql) {
            $query->appendQuery($withExtra);
        }
        echo $query; exit;

The generated query was:

SELECT content.*, category.* FROM content INNER JOIN category ON content.category_id = category.id WHERE category.id = ?

I decided to replace my command by your example:

<?php $mapper->comment(array("created_at >"=>strtotime('today')))
             ->post(array("created_at >"=>strtotime('7 days ago')))
             ->author[7]
             ->fetchAll();

And the generated query was actually:

SELECT comment.*, post.*, author.* FROM comment INNER JOIN post ON comment.post_id = post.id INNER JOIN author ON post.author_id = author.id WHERE author.id = ?

It seems it's only taking into account the last condition from the join.

Start with library/Respect/Relational/Mapper.php around line 223 and reproduce the documented multi-table examples. Trace how the query is generated for conditions on content, comment, and post alongside the final joined-table condition. Done means predicates from every specified table are represented in the generated SQL, rather than only the last join condition.