develop code (DT editor) from https://blog.rstudio.com/2018/03/29/dt-0-4/ , rstudio/DT#480 by Yihui Xie
This code add undo and redo Function and undo concept code from concept code (undo) from https://rdrr.io/github/GerkeLab/grkShinyThings/man/undoHistory.html