Add some fixes for URL links, since PDFAnnotationLink turns relative paths into http: URLs.  Don't show the hover window for links outside the document.
Add some fixes for URL links, since PDFAnnotationLink turns relative paths into http: URLs.  Don't show the hover window for links outside the document.

JackieXie168/skim,JackieXie168/skim,JackieXie168/skim,JackieXie168/skim,JackieXie168/skim