Adds a support for custom OpenCart models

OCMod "Custom Model Support"

<?xml version="1.0" encoding="utf-8"?>
<modification>
    <name>Custom Model Support</name>
    <code>custom_model_support</code>
    <version>1.0</version>
    <author>Sergii Matrunchyk</author>
    <link>mailto: [email protected]</link>
    <file path="system/engine/loader.php">
        <operation>
            <search trim="true"><![CDATA[
                $model = str_replace('../', '', (string)$model);
            ]]></search>
            <add position="after"><![CDATA[
        /* <custom_model_support> */
        $mod_file = DIR_MODIFICATION . ((defined('HTTP_CATALOG')) ? 'admin' : 'catalog') . '/model/' . $model . '.php';
        /* </custom_model_support> */]]></add>
        </operation>
        <operation>
            <search trim="true"><![CDATA[
                $this->registry->set('model_' . str_replace('/', '_', $model), new $class($this->registry));
            ]]></search>
            <add position="after"><![CDATA[
        /* <custom_model_support> */
        } elseif (file_exists($mod_file)) {
		    include_once($mod_file);

			$this->registry->set('model_' . str_replace('/', '_', $model), new $class($this->registry));
			/* </custom_model_support> */]]></add>
        </operation>

    </file>
</modification>