Fix ManFileParser to support asciidoctor == section syntax

[tristantarrant]

Summary

This PR fixes ManFileParser to properly conform to the asciidoctor manpage specification, particularly for section heading formats.

Fixes #683

Problem

The current implementation only supports the underline section format:

SECTION
-------

According to the asciidoctor spec, manpage sections should use the standard AsciiDoc heading syntax:

== Section Title

This meant that all standard asciidoctor manpage files using == section syntax failed to parse.

Changes

ManSection.java

• Added support for == Section syntax (standard asciidoctor format)
• Maintains backward compatibility with underline format (Section\n-----)
• Cleans up unused variables

ManFileParser.java

• Fixed header validation to support both = title and title\n==== formats
• Properly validates :doctype: manpage attribute
• Provides clear error messages for invalid headers

Test Suite

• Added comprehensive test suite ManFileParserTest.java with 19 test cases
• Tests cover:
  • == section syntax parsing
  • Underline section syntax parsing
  • Mixed format support
  • Header validation (both title formats)
  • Doctype validation
  • Edge cases (empty sections, anchors, aliases)
  • Parser reuse and different column widths
• All 19 tests pass ✅

Test Resources

• asciitest3_with_equals.txt - Complete manpage using == SECTION syntax
• asciitest4_minimal.txt - Minimal valid manpage header
• asciitest5_mixed_format.txt - Mixed == and underline formats

Backward Compatibility

✅ Full backward compatibility maintained

• Existing man page files using underline format continue to work
• Both formats can coexist in the same file
• All existing tests pass

Test Results

Tests run: 19, Failures: 0, Errors: 0, Skipped: 0
Full test suite: BUILD SUCCESS

🤖 Generated with Claude Code