You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query-continue>
    <alltransclusions gatcontinue="IRidium_Project|1093" />
  </query-continue>
  <query>
    <pages>
      <page pageid="57" ns="0" title="IRidium GUI Editor" />
      <page pageid="61" ns="0" title="IRidium Gate" />
      <page pageid="798" ns="0" title="Компоненты программного комплекса iRidium" />
      <page pageid="1089" ns="0" title="Описание iRidium для My Home" />
      <page pageid="1093" ns="0" title="Описание iRidium для Domintell" />
    </pages>
  </query>
</api>