Fix in editor.py for windows user

A call to gnsync under windows raises an error
"Error while parsing text to html. Content must be an UTF-8 encode."
A call to gnsync under windows raises an error ;
"Error while parsing text to html. Content must be an UTF-8 encode."
Global name 'self' is not defined when calling gnsync. I replaced it
with an explicit call to the Editor object.

+2 typos