staticref shortcode: Add `"newtab"` option to open link in new tab

exampleSite/content/post/writing-markdown-latex.md

@@ -60,7 +60,9 @@ A numbered figure with caption:
     
 To enable linking to a file, such as a PDF, first place the file in your `static/files/` folder and then link to it using the following form:
 
-    {{%/* staticref "files/cv.pdf" */%}}Download my CV{{%/* /staticref */%}}
+    {{%/* staticref "files/cv.pdf" "newtab" */%}}Download my CV{{%/* /staticref */%}}
+
+The optional `"newtab"` argument for `staticref` will cause the link to be opened in a new tab.
 
 ## Emojis
 

layouts/shortcodes/staticref.html

@@ -1 +1,3 @@
-<a href="{{ .Page.Site.BaseURL }}{{ .Get 0 }}"/>{{ .Inner }}</a>
+<a href="{{ .Get 0 | absURL }}"{{ if len .Params | eq 2 }} target="_blank"{{ end }}>
+  {{ .Inner }}
+</a>