refactor the code to search for the beginning of a paragraph a bit to

refactor the code to search for the beginning of a paragraph a bit to
fix some inaccuracies and eliminate the need for recursion; it now uses
almost the same logic as the code to search for the end of a paragraph,
which makes it somewhat easier to understand

git-svn-id: svn://svn.savannah.gnu.org/nano/trunk/nano@1823 35c25a1d-7b9e-4130-9fde-d3aeb78583b8