Unicode support in TextCells

[mora]

In a TextCell? (shift+click on the blue line) I write some letters:

​http://www.math.bme.hu/~morap/sage_textcell1.png

after I save it. It looks fine:

​http://www.math.bme.hu/~morap/sage_textcell2.png

but when I double click on it to edit, then I get:

​http://www.math.bme.hu/~morap/sage_textcell3.png

That's the problem. I could not find out what (Python or TinyMCE) converts the special characters to html entities (for example é to é), but it does not convert all of them.

The patch solves the problem. Without it the html code looks like:

​http://www.math.bme.hu/~morap/sage_textcell4.png

using the patch everything's fine. The html code after applying the patch:

​http://www.math.bme.hu/~morap/sage_textcell5.png

[mora]

The Ticket 6464 is nearly the same. I suggest the solution of 6464 to use.

[kcrisman]

To release manager: this should be closed as a duplicate of #6464, as mentioned above.

[mvngu]

Closing this as a duplicate of #6464.