Update screenshots and files that reference them

The screenshots are more recent (including some new ones).

The welcome email images have not been updated as some things have to be
answered before that can be done.

The current files were renamed to be shorter as well.

next/submit.html

@@ -435,34 +435,38 @@ might be offline and unreachable as a website.</p>
 <p>To login, open <a href="https://submit.ioccc.org">https://submit.ioccc.org</a>
 in your browser. Fill in your login credentials and click “Login”.
 It might look something like:</p>
-<p><img src="../png/submit-server-login.png"
+<p><img src="../png/submit.login.png"
  alt="submit server login page"
  width=710 height=344></p>
-<p>If you’ve not logged in before, you’ll have to change your password first. See
-the file <a href="pw-change.html">pw-change.html</a> for more details. After that you will
-have to log back in.</p>
+<p><strong>NOTE</strong>: if the contest is NOT open you will see something like this instead:
+<img src="../png/submit.contest-closed.png"
+ alt="submit server contest closed"
+ width=710 height=806></p>
+<p>Assuming it is open, and if you’ve not logged in before, you’ll have to change
+your password first. See the file <a href="pw-change.html">pw-change.html</a> for more
+details. After that you will have to log back in.</p>
 <p>Once you’ve logged in, you will see submit slots. Each slot is for one
 submission so if you update a submission, make sure you choose the right one so
-you do not overwrite the wrong one!</p>
+you do not replace the wrong one!</p>
 <p>Here is what it looks like without any uploads and no slot selected:</p>
-<p><img src="../png/submit-server-slots.png"
+<p><img src="../png/submit.slots.png"
  alt="submit server slots"
  width=710 height=806></p>
 <p>Select a slot and then select a file by clicking the button “Choose File”. After
 doing this, it should look something like:</p>
-<p><img src="../png/submit-server-slot-file.png"
+<p><img src="../png/submit.slot-file.png"
  alt="submit server slot and file selected"
  width=717 height=865></p>
 <p>If you need to change the file to upload, you can mouseover the file and click
 it. If you wait a moment it’ll show the current filename. It will look something
 like this:</p>
-<p><img src="../png/submit-server-change-file.png"
+<p><img src="../png/submit.change-file.png"
  alt="submit server change file"
  width=717 height=865></p>
 <p>Once you’re certain you have selected the correct file, click “Submit”, below
 the file selection step.</p>
 <p>When it’s uploaded it should look something like this:</p>
-<p><img src="../png/submit-server-submission-uploaded.png"
+<p><img src="../png/submit.submission-uploaded.png"
  alt="submit server submission uploaded"
  width=717 height=525></p>
 <p>Here you see the details, in particular:</p>
@@ -481,14 +485,14 @@ tarball listing)</li>
 your submissions. Here is what it will look like when the judges have verified
 that your tarball / submission has been validated (NOT judged), by <code>txzchk(1)</code>
 and <code>chkentry(1)</code>:</p>
-<p><img src="../png/submit-server-status-updated.png"
+<p><img src="../png/submit.status-updated.png"
  alt="submit server status updated"
  width=717 height=217></p>
 <p>For details on <code>txzchk</code>, see the
 FAQ on “<a href="../faq.html#txzchk">txzchk</a>”.</p>
 <p>For details on <code>chkentry</code>, see the
 FAQ on “<a href="../faq.html#chkentry">chkentry</a>”.</p>
-<p>If you need more information on what <code>chkentry</code> checks, see the
+<p>If you need more information on the two JSON files, see
 FAQ on the <a href="../faq.html#info_json">“.info.json file</a>”
 and the
 FAQ on the “<a href="../faq.html#auth_json">.auth.json file</a>”.</p>