This is easier to type:

perl -pe 'chomp;s/^\+//||s/^/\n/;END{print"\n"}' # Unix
perl -pe "chomp;s/^\+//||s/^/\n/;END{print qq.\n.}" # Win32
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And you can drop the END{...} part if you just append an extra blank line to the input or don't mind the missing final newline on the output.