/main_css_action
wrapper to make style.skin public

Sourcecode in Site/actions.js:
1:   function main_css_action() {
2:      res.dependsOn(this.modifytime);
3:      res.dependsOn(res.handlers.layout.modifytime);
4:      res.dependsOn(res.handlers.layout.skins.getSkinSource("Site", "style"));
5:      res.digest();
6:      res.contentType = "text/css";
7:      this.renderSkin("style");
8:      return;
9:   }