revert the marked replace code; it's hackish, and there appears to be no

revert the marked replace code; it's hackish, and there appears to be no
easy way to make it work with the internal spell checker as is; it
should eventually be reimplemented to work at the findnextstr() level

git-svn-id: svn://svn.savannah.gnu.org/nano/trunk/nano@2031 35c25a1d-7b9e-4130-9fde-d3aeb78583b8