& converts to & in textareas

[GaurangTandon]

Typing a snippet (abcd&efgh) into a textarea results in (abcd&efgh). This issue does not occur in contenteditable divs. The same problem is with < or >.

Also, editing such a snippet first shows abcd&efgh in the textarea editor.

This issue is definitely part of the over-arching problem of the weird implementation of the dual textbox. Need a more robust fix for that first. (related #191) One solution may be to simply prepend a !IS_RTE_SNIPPET! text to each of the snippets that are created using the rich editor.