Fix nested complex types generation in schemas

See http://answers.nuxeo.com/questions/7408/bug-nuxeo-studio-generating-syntactically-invalid-schema-for-nested-complex-types

Ok, here's what I did (all within studio):

• go to Content Model->Schemas
• click +New schema
• enter featureid "bugtest" and prefix "bugtest", check the "allow complex nested types"
• add a field named "nest1" , type "Complex", check "Multivalued" on "nest1" field, click Edit next to Complex
• add a field named "nest2", type "Complex", check "Multivalued" on "nest2" field, click Edit next to Complex
• add a field named "foo" type String
• click Save

Switch over to Nuxeo DM

• go to Admin Center
• click Update Center
• click Update

In Nuxeo DM logs, i see this:

2013-11-22 07:22:19,720 ERROR [http-bio-0.0.0.0-8080-exec-5] [org.nuxeo.ecm.core.schema.XSDLoader] FatalError: Unexpected <xs:complextype> appears at line 44 column 52 2013-11-22 07:22:19,721 ERROR [http-bio-0.0.0.0-8080-exec-5] [org.nuxeo.ecm.core.schema.SchemaManagerImpl] org.xml.sax.SAXParseException; systemId: file:/Users/rtrotter/Downloads/nuxeo-cap-5.8-tomcat/nxserver//schemas/bugtest.xsd; lineNumber: 44; columnNumber: 52; Unexpected <xs:complextype> appears at line 44 column 52

For completeness, here are lines 35 through 55 of bugtest.xsd as it got generated from studio:

<xs:element name="nest1" type="nxs:bugtest_nest1ListType"/>
  <xs:complextype name="bugtest_nest1ListType">
    <xs:sequence>
      <xs:element name="item" type="nxs:bugtest_nest1Type" minoccurs="0" maxoccurs="unbounded"/>
    </xs:sequence>
  </xs:complextype>
  <xs:complextype name="bugtest_nest1Type">
    <xs:sequence>
      <xs:element name="nest2" type="nxs:bugtest_nest2ListType"/>
      <xs:complextype name="bugtest_nest2ListType">
        <xs:sequence>
          <xs:element name="item" type="nxs:bugtest_nest2Type" minoccurs="0" maxoccurs="unbounded"/>
        </xs:sequence>
      </xs:complextype>
     <xs:complextype name="bugtest_nest2Type">
       <xs:sequence>
         <xs:element name="foo" type="xs:string"/>
       </xs:sequence>
     </xs:complextype>
   </xs:sequence>
</xs:complextype>