Mathslate is now in a reasonably usable form, and I have repackaged it in a single plugin for Tinymce for Moodle 2.5 and Moodle 2.6 (unzip in lib/editor/tinymce/plugins/). When Moodle 2.7 is finalized, I will finish adding Atto and TinyMCE4 if they are included.
Mathslate is a javascript mathematical expression constructor. It relies on MathJax and YUI for the lower level functions. Users create and manipulate expressions from predefined templates or from TeX commands. The associated TeX code is displayed as the expression is manipulated. It is configurable with CSS and by editing a JSON file to change available templates. The TeX code is inserted into TinyMCE currently although it may configured for other input/output forms without a lot of trouble.