GH-4336: Fix "Powered by TinyMCE" breaking XHTML pages
GH-4336: Fix "Powered by TinyMCE" breaking XHTML pages

The “Powered by TinyMCE” link breaks XHTML pages when inserted into the page (“not well-formed” XML processing error reported by Firefox) because ampersands are not properly escaped.

tinymce/tinymce,TeamupCom/tinymce,FernCreek/tinymce,tinymce/tinymce,FernCreek/tinymce,TeamupCom/tinymce,FernCreek/tinymce,danielpunkass/tinymce,danielpunkass/tinymce,tinymce/tinymce,danielpunkass/tinymce