Adding D keybinding to textarea editing to delete everything until EOL

Thanks Daniel Schaffrath for the patch

content/editor.js

@@ -323,6 +323,10 @@ liberator.Editor = function () //{{{
         },
         { flags: liberator.Mappings.flags.COUNT });
 
+    liberator.mappings.add([liberator.modes.TEXTAREA],
+        ["D"], "Delete the characters under the cursor until the end of the line",
+        function () { liberator.editor.executeCommand("cmd_deleteToEndOfLine"); });
+
     liberator.mappings.add([liberator.modes.TEXTAREA],
         ["o"], "Open line below current",
         function (count)