add multibyte/wide character support to input_tab(), so that we don't
end up with a string that contains only part of a multibyte character
during tab completion


git-svn-id: svn://svn.savannah.gnu.org/nano/trunk/nano@2560 35c25a1d-7b9e-4130-9fde-d3aeb78583b8
2 files changed