Add support for a target variable in regular links.

This will initially be used for supporting "post://" links.

src/context/regular_link.rs

@@ -11,6 +11,7 @@ use super::RenderObject;
 #[serde(tag = "type")]
 #[serde(rename = "regular_link")]
 pub(crate) struct RenderRegularLink {
+    target: String,
     raw_link: String,
     children: Vec<RenderObject>,
     post_blank: organic::types::PostBlank,
@@ -25,7 +26,13 @@ render!(RenderRegularLink, IRegularLink, original, render_context, {
         ret
     };
 
+    let target = original
+        .target
+        .generate_final_target()?
+        .unwrap_or_else(|| "".to_owned());
+
     Ok(RenderRegularLink {
+        target: target,
         raw_link: original.raw_link.clone(),
         children,
         post_blank: original.post_blank,