title: Having issues accessing `SQLAlchemyAutoSchema` from flask-marshmallow, though I have the latest version of flask-marshmallow installed
body: <p>I've tried various versions of flask-marshmallow, and have installed and uninstalled the latest version as well. As you can see below, I've also verified that I'm using the latest version which should have <code>SQLAlchemyAutoSchema</code> but I'm not able to access it. </p>
  
  <pre><code>&gt;&gt;&gt; import flask_marshmallow
  &gt;&gt;&gt; dir(flask_marshmallow)
  ['EXTENSION_NAME', 'LooseVersion', 'Marshmallow', 'Schema', '__all__', '__builtins__', '__cached__', '__doc__', '__file__', '__loader__', '__name__', '__package__', '__path__', '__spec__', '__version__', '__version_info__', '__warningregistry__', '_attach_fields', 'base_fields', 'compat', 'exceptions', 'fields', 'flask_sqlalchemy', 'has_sqla', 'pprint', 'schema', 'warnings']
  &gt;&gt;&gt; flask_marshmallow.__version__
  '0.12.0'
  &gt;&gt;&gt; flask_marshmallow.Marshmallow()
  &lt;flask_marshmallow.Marshmallow object at 0x10300de48&gt;
  &gt;&gt;&gt; flask_marshmallow.Marshmallow().SQLAlchemyAutoSchema
  Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
  AttributeError: 'Marshmallow' object has no attribute 'SQLAlchemyAutoSchema'
  </code></pre>
  
  <p>I'm out of ideas on what could be causing this. Anyone seen this before?</p>