0.12.24

[eshellman]

• in generated header, use same method as Autocat3 for rendering PubInfo -
• in generated header, render each creator on a separate line
• don't set exclude_encodings param for html5lib parser
• improve info log message for parser selection
• header identification was messed up by language tags in the marker. removed them
• MIN_CHUNK_SIZE reduced from 1024 bytes to 256 bytes. fixes #147
• update to libgutenberg 0.10.13 to recognize plural creator roles in metadata header