Add keyboard shortcut for mark-older-as-read: the o key. (Oh, not zero.)

Evergreen/MainWindow/Keyboard/GlobalKeyboardShortcuts.plist

@@ -60,6 +60,12 @@
 		<key>action</key>
 		<string>markAllAsReadAndGoToNextUnread:</string>
 	</dict>
+	<dict>
+		<key>key</key>
+		<string>o</string>
+		<key>action</key>
+		<string>markOlderArticlesAsRead:</string>
+	</dict>
 	<dict>
 		<key>key</key>
 		<string>u</string>

Evergreen/Resources/KeyboardShortcuts/KeyboardShortcuts.html

@@ -41,12 +41,13 @@
 <tr><td>Go to next unread</td><td>+</td></tr>
 <tr class="backgroundColorRow"><td>Mark as read</td><td>r</td></tr>
 <tr><td>Mark all as read</td><td>k</td></tr>
-<tr class="backgroundColorRow"><td>Mark all as read, go to next unread</td><td>l (lowercase L)</td></tr>
-<tr><td>Mark as unread, go to next unread</td><td>m</td></tr>
-<tr class="backgroundColorRow"><td>Mark as unread</td><td>u</td></tr>
-<tr><td>Open in browser</td><td>b or return or enter</td></tr>
-<tr class="backgroundColorRow"><td>Previous subscription</td><td>a</td></tr>
-<tr><td>Next subscription</td><td>z</td></tr>
+<tr class="backgroundColorRow"><td>Mark older articles as read</td><td>o</td></tr>
+<tr><td>Mark all as read, go to next unread</td><td>l (lowercase L)</td></tr>
+<tr class="backgroundColorRow"><td>Mark as unread, go to next unread</td><td>m</td></tr>
+<tr><td>Mark as unread</td><td>u</td></tr>
+<tr class="backgroundColorRow"><td>Open in browser</td><td>b or return or enter</td></tr>
+<tr><td>Previous subscription</td><td>a</td></tr>
+<tr class="backgroundColorRow"><td>Next subscription</td><td>z</td></tr>
 
 <tr><td colspan="2">&nbsp;<br /></td></tr>
 <tr><td colspan="2" class="tableTitleRow">Left sidebar only…</td></tr>