since the total number of lines in a file is the same as the number of

since the total number of lines in a file is the same as the number of
its last line when all its lines are numbered properly, use that in
place of openfile->totlines, and eliminate references to
openfile->totlines

git-svn-id: svn://svn.savannah.gnu.org/nano/trunk/nano@2933 35c25a1d-7b9e-4130-9fde-d3aeb78583b8