TinyMCE Upgrade for J2.5 to latest 3.5.11

This upgrades tinymce in Joomla 2.5 to the latest version in the 3.x series (note joomla 3.x is in the 4.x series). This fixes a variety of issues including IE11 support - see the official tiny changelog for more info.

To test just ensure tiny editor still works in 2.5.x as previously