Error page dropdown in the Settings

[farzindev]

We need a dropdown in the settings (probably on the advanced tab) that can select a page from created Pages. and that page would be the 404 page.

So admins can create a 404 page in the Pages with the title of Not Found or anything else with any content they want just like a normal page. and then they go to the settings and set that page as the Error page.

If they didn't set any page as the error page, in case of 404 errors we show the default HTML error page that comes with Blogifier to the visitor.