Code Review: YamlParse2

Thanks for your comments, Tomas. Here is another try.

tfpt review “/shelveset:YamlParse2;REDMOND\olegtk”
Comment :
Implements Bignum support.
Refactores constructors hierarchy by decoupling constructors (those
building Ruby objects from Nodes) and composers (those building Nodes
from Yaml source) and introducing NodeProvider to be used by
Adds preliminary support for YamlNode and Implements
Implements YAML::parse, YAML::parse_documents and YAML::parse_file
Removes YamlDocument class - duplicate functionality.
Fixes circular referenced objects to_yaml serialization.