in titlebar(), make sure that the (mv)?waddnstr() calls take the proper

in titlebar(), make sure that the (mv)?waddnstr() calls take the proper
number of bytes when using multibyte characters, so that multibyte
strings aren't prematurely cut off; also allow the "View" state to be
displayed when a filename is passed in, in case we're in multibuffer
mode and inside the file browser

git-svn-id: svn://svn.savannah.gnu.org/nano/trunk/nano@2424 35c25a1d-7b9e-4130-9fde-d3aeb78583b8