* ext/psych/yaml/emitter.c: merge libyaml 0.1.5
* ext/psych/yaml/loader.c: ditto
* ext/psych/yaml/parser.c: ditto
* ext/psych/yaml/reader.c: ditto
* ext/psych/yaml/scanner.c: ditto
* ext/psych/yaml/writer.c: ditto
* ext/psych/yaml/yaml_private.h: ditto