• Fix bug in emitter (strings starting with % must be quoted)
  
• Implement loading of schema classes not prefixed with YAML::PP::Schema
  (PR#8 @pplu)
  
• Implement loading of perl objects
  
• Fix line number of multiline tokens
  
• Refactor parser/lexer. All tokens (except indentation) are now
  parsed by the grammar.
  
• Change arguments of resolver callback
  
• Add a catchall resolver for scalars