[Development] Stop insertion QTextEdit unicode character.

[kang joni]

Sorry for my bad English, Quick grep-ing in qtbase 5.6
src/widgets/widgets/qwidgettextcontrol.cpp at line 3254 just found my
case here. I don't know how to use this. And I didnt aware any of docs
explaining this. If you right click on editable QLineEdit or QTextEdit
there should be "Insert Unicode control
character", sorry my former title was bit wrong typo here. So,  back
to my case whenever I type from ASCII and then accidentally clicking
from "Insert Unicode control
character" with any selecting LRM,RLM  ... etc I didn't know how to
switch back to type ASCI I character with exception close app window
and reopen it again, and everything would be normal again. This all
happen in all Qt apps.