Add post and image deletion

This one was kind of a doozy. This also adds a custom 403 error page and
fixes some permission denied behavior that I was having issues with for
a while.

This is also set up in a way that hopefully will allow me to easily
implement user post deletion.

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

board/static/board/post.js

@@ -3,7 +3,8 @@ const OPEN = "open";
 const CLOSED = "closed";
 const replyWindowName = "reply-window";
 const postWindowName = "post-window";
-const reportWindowName = "report-window"
+const reportWindowName = "report-window";
+const deleteWindowName = "delete-window";
 const WINDOW_INNER_PADDING = 25;
 
 
@@ -204,6 +205,31 @@ function openReportWindow(reportUrl) {
     reportWindow.show();
 }
 
+////////////////////////////////////////////////////////////////////////////////
+// Post delete window
+////////////////////////////////////////////////////////////////////////////////
+function getDeleteWindow() {
+    return window.top.jsFrame.getWindowByName(deleteWindowName);
+}
+
+function openDeleteWindow(deleteUrl) {
+    if (window.top.jsFrame.containsWindowName(deleteWindowName)) {
+        getDeleteWindow().closeFrame();
+    }
+
+    let deleteWindow = window.top.jsFrame.create({
+        title: "Deleting post",
+        name: deleteWindowName,
+        width: 475,
+        url: deleteUrl,
+    });
+    $(deleteWindow.iframe, "iframe").on("load", () => {
+        fitWindowToContent(deleteWindow);
+        deleteWindow.setResizable(false);
+    });
+    deleteWindow.show();
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // Post hiding
 ////////////////////////////////////////////////////////////////////////////////
@@ -365,4 +391,13 @@ window.menuItemFactories.push(
                     addHiddenPost(id);
                 }
             })
+);
+window.menuItemFactories.push(
+    (postElement) => $("<a>")
+        .text("Delete post")
+        .attr("href", "#")
+        .on("click", (e) => {
+            e.preventDefault();
+            openDeleteWindow($(postElement).attr("data-delete-url"));
+        })
 );