title: Extra field in manyToMany relationship
body: <p>I have two tables: <code>users</code> and <code>estates</code></p>
  
  <p>A user can be "linked" to multiple estates, and an estate can be "linked" to many users. To handle this manyToMany relationship, I created a "joinTable" estatesUsers in which the primary key is actualy a composite one involving the two foreign keys <code>userId</code> and <code>estateId</code>.</p>
  
  <p>This was fine until I wanted to add extra fields to this table.</p>
  
  <p>I read that when adding extra fields for such a table, the relationship is not a "manyToMany" anymore but two "oneToMany" relationship instead for each original entities.</p>
  
  <p>My problem is that Doctrine still not consider this table (was the join table) and skip it when I run <code>php app/console doctrine:mapping:import AppBundle yml</code></p>
  
  <p>How can I get the command line tool to handle correctly those relationships and generate this new entity (the yml schema files) ?</p>
  
  <p>Extra question: how do I command the tool (inside the yml schema files) to create a repository class for each entity before running <code>php app/console doctrine:generate:entities MyBundle</code> ?</p>
  
  <p>Thank you !</p>