This is the on disk format serialiser and deserialise for
Foswiki topics legacy .txt format.
WARNING this is only for Foswiki::Meta objects.
ClassMethod new( $class, ) → $cereal
StaticMethod dataEncode( $uncoded ) → $coded
Encode meta-data field values, escaping out selected characters.
The encoding is chosen to avoid problems with parsing the attribute
values in embedded meta-data, while minimising the number of
characters encoded so searches can still work (fairly) sensibly.
The encoding has to be exported because Foswiki (and plugins) use
encoded field data in other places e.g. RDiff, mainly as a shorthand
for the properly parsed meta object. Some day we may be able to