This only adds newline characters to make the existing text blocks act like
"blockquote" or "code block" syntax in Markdown, asciidoc, and others.
This was accomplished by manually reviewing the output of this script:
```bash
for f in *.txt; do
cat $f | python -c "import sys,re;print(re.sub(r'(\n {0,3}[^ \n][^\n]*\n)( {4,}[^\n]*)', r'\1\n\2', sys.stdin.read()))" > ${f}.tmp
mv ${f}.tmp $f
done
```