Add RTL support

[eyy]

https://en.wikipedia.org/wiki/Bi-directional_text

Thanks.

[amitassaraf]

+1

[abublihi]

Hi, I have examine Editor.js and it is mostly support RTL,

you can find the what i have done on this codepin https://codepen.io/anon/pen/zQqeeM

[ShahriarKh]

Is this implemented? If so, can somebody please explain how to use it?

RTL/LTR buttons in Word: