[with patch and spkg] Make in-line wysiwyg editor for text cells using TinyMCE

[jasongrout]

This ticket splits off part of #4267.

It depends on #4704

Component: notebook

Issue created by migration from https://trac.sagemath.org/ticket/4705

[jasongrout]

Attachment: tinymce-editable.patch.gz

[jasongrout]

comment:1

The spkg is at http://sage.math.washington.edu/home/jason/notebook/tinyMCE-3.2.0.2.spkg

[TimothyClemans]

comment:5

Works for me Apply #4674, #3767, #4704, #4705