Added underscore prefix to functions used only internally:
- _strip_tags_and_truncate (used only in parse_post_file)
- _parse_headers (used only in parse_post_file)
- _rfc_2822_format (used only in parse_post_file)
- _make_links_absolute (used only in parse_post_file)
- _strip_html_tags (used only in parse_post_file)
- _get_friendly_date (used only in _setup_page_params)
- _exit_program (used only in monitor.py main loop)
This improves encapsulation by clearly marking implementation details.