* Added YamlPresenter*Error exceptions
* Added raises pragma to present()
* catch exceptions from YamlStream and Stream in present() and
put them as cause into YamlPresenter*Error
* Added loadToJson() proc
* Give "~" the type hint yTypeNull
* Always output "null" for yTagNull/yTypeNull scalars when
presenter is in JSON mode
* Added YamlWarningCallback that may be used to capture
parser warnings
* Removed yamlWarning as event kind
* Replaced checks for well-formedness in presenter with asserts
* Added checks for JSON compatibility of YamlStream in presenter
* Added proper type hints for special float values in
serializer to be able to check for them in the presenter
* Yield tag of custom type serialization when using ytsRootOnly,
but don't yield tags of map keys or values
* Yield proper tag of Table[K, V] serialization if requested
* renamed dumper.nim to presenter.nim to conform to YAML spec
* Fixed a bug in the lexer where an error would be raised if
characters not allowed in tag shorthands are used in local tags
* Fixed processing of object tags for all kinds of root nodes in Parser
* Improved dumper to output a space after a local tag
* Renamed some enumeration types to conform better to the YAML spec
* Added secondaryPrefix to YamlTagLibrary
* Added possibility to control tag output style independently from
presentation style in serializer
* Created local tags for all types that are serialized and use them in
construction and serialization
* Better JSON serialization (map bool literals to true/false if
possible)
* Fixed a problem where the tag of block sequence would be
wrongly placed
* Always output "" when dumping empty strings
* Added helper functions to create YamlStreamEvents.
* Moved procs for YamlStreamEvents to private/events.nim
* renamed dump() to present()
* Added dump() and load() to yaml.serialization
Felix Krause