Directly access to ctlr in staticMathTextareaEvents

In 6e1c74abe96c75ca44f82c26939a51f288c0217f, staticMathTextareaEvents
was moved from a function that takes in `root` as a parameter, to a
method on the Controller, so now can directly access the controller as
`this`.
Use `ctlr` instead of `this` in Controller methods

Minifies better, and can be used in closures.

Recommend --word-diff-regex='\w+|\S' to view diff.
Move `.blurred` from root block to Controller

Recommend --word-diff-regex='\w+|\S' to view diff.
Move `.editable` from root block to Controller
Move `.textbox` from root block to Controller
publicapi.js uses controller instead of root block

Recommend --word-diff-regex='\w+|.' to view diff.