Don't dim additional Logged-In Users options in Pro Preview

This follows the Pro Preview behavior of other Pro-only options like
the HTML Compressor and the Auto-Cache Engine.

Related: wpsharks/comet-cache#768

src/includes/classes/MenuPageOptions.php

@@ -602,8 +602,8 @@ public function __construct()
             echo '      <i class="si si-sitemap si-4x" style="float:right; margin: 0 0 0 25px;"></i>'."\n";
             echo '      <p>'.sprintf(__('<strong>Exception (Membership Sites):</strong> If you run a site with many users and the majority of your traffic comes from users who ARE logged-in, please choose: <code>Yes (maintain separate cache)</code>. %1$s will operate normally; but when a user is logged-in, the cache is user-specific. %1$s will intelligently refresh the cache when/if a user submits a form on your site with the GET or POST method. Or, if you make changes to their account (or another plugin makes changes to their account); including user <a href="http://codex.wordpress.org/Function_Reference/update_user_option" target="_blank">option</a>|<a href="http://codex.wordpress.org/Function_Reference/update_user_meta" target="_blank">meta</a> additions, updates &amp; deletions too. However, please note that enabling this feature (e.g., user-specific cache entries); will eat up MUCH more disk space. That being said, the benefits of this feature for most sites will outweigh the disk overhead (e.g., it\'s NOT an issue in most cases). Unless you are short on disk space (or you have MANY thousands of users), the disk overhead is neglible.', SLUG_TD), esc_html(NAME)).'</p>'."\n";
             echo '      <p><select name="'.esc_attr(GLOBAL_NS).'[saveOptions][when_logged_in]" data-toggle="enable-disable" data-enabled-strings="1,postload" data-target=".-logged-in-users-options">'."\n";
-            echo '            <option value="0"'.selected($this->plugin->options['when_logged_in'], '0', false).'>'.__('No, do NOT cache; or serve a cache file when a user is logged-in (safest option).', SLUG_TD).'</option>'."\n";
-            echo '            <option value="postload"'.selected($this->plugin->options['when_logged_in'], 'postload', false).'>'.__('Yes, and maintain a separate cache for each user (recommended for membership sites).', SLUG_TD).'</option>'."\n";
+            echo '            <option value="0"'.(!IS_PRO ? '' : selected($this->plugin->options['when_logged_in'], '0', false)).'>'.__('No, do NOT cache; or serve a cache file when a user is logged-in (safest option).', SLUG_TD).'</option>'."\n";
+            echo '            <option value="postload"'.(!IS_PRO ? ' selected' : selected($this->plugin->options['when_logged_in'], 'postload', false)).'>'.__('Yes, and maintain a separate cache for each user (recommended for membership sites).', SLUG_TD).'</option>'."\n";
             if ($this->plugin->options['when_logged_in'] === '1' || get_site_option(GLOBAL_NS.'_when_logged_in_was_1')) {
                 update_site_option(GLOBAL_NS.'_when_logged_in_was_1', '1');
                 echo '            <option value="1"'.selected($this->plugin->options['when_logged_in'], '1', false).'>'.__('Yes, but DON\'T maintain a separate cache for each user (I know what I\'m doing).', SLUG_TD).'</option>'."\n";