Don't output partial UTF-8 characters in ksh emacs mode. Instead, try to read a

Don't output partial UTF-8 characters in ksh emacs mode. Instead, try to read a
complete UTF-8 character first. Fixes an issue while running ksh in tmux where
UTF-8 characters inserted in columns other than the last one are discarded.

With help from nicm@ and schwarze@ who also wrote the UTF-8 validation, thanks!

ok schwarze@