allow to specify s.linkURL in s_code

s.linkName is great for changing how a link is displayed in SC, but it's limited to 100 chars and not clickable. The link URL is not changable but has a limit of 255 chars.

Please allow to specify s.linkURL (pev1) in the javascript, as we can specify s.linkName (pev2) for automatic link-tracking and using s_doPlugins.