Remove error alert messages to users in ajaxmappane.templ

[gabrimonfa]

When errors occur in requests issued by ajaxmappane.templ, users are presented with a javascript alert which is not informative nor localized.

Since the issue is always not "user serviceable" and almost always all continues to work correctly after the alert, there no need to display it to the users.

Refining error messages has been already the subject of several closed tickets but no one apply perfectly.

I propose to comment out the "alert" in the following function of ajaxmappane.templ:

RequestFailed(text)

and maybe in

OnMapOverlayImageLoadedError(e)

[jng]

Fixed r6549