curses textpad.py UTF-8 support

[elig0n]

is non existent. Unicode input text won't show up.

It probably needs to be rewritten with get_wch() as was suggested in the following SO question before get_wch() was implemented, together with proper key code parsing (in do_command()) and probably more as to prevent breakage
[ https://stackoverflow.com/questions/42510606/python-curses-textpad-textbox-keyboard-input-not-working-with-german-umlauts ].