Release v3.16.0

Added

• Allow True in allowed_css_properties mappings to mix properties using normal sanitizer checks with properties restricted by literal or regex value rules.

Fixed

• Process a leading NUL through document and head recovery before discarding it in the body, including text mixed with character references. Preserve following body whitespace, head-element placement, and text source locations.
• Keep whitespace after </head> under <html> until body content begins, including encoded whitespace and whitespace followed by other text in the same token.