space) all over the code, properly detect whether we have strcasestr()
and only use nstristr() if we don't, and bump up CVS build requirements
to account for setting _GNU_SOURCE when running the test programs for
both


git-svn-id: svn://svn.savannah.gnu.org/nano/trunk/nano@1730 35c25a1d-7b9e-4130-9fde-d3aeb78583b8