fix typo at https://github.com/ruby/ruby/pull/500 and https://github.com/ruby/ruby/pull/506
Merge pull request #180 from hsbt/fix-typo

backport ruby/ruby#500 and ruby/ruby#506
* 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
bumping to 2.0.3
* ext/psych/yaml/config.h: bump libyaml to 0.1.5
merge from ruby trunk
bumping version
remove unused variables
Merge pull request #186 from hsbt/backport-rubycore

remove unused variables
backport from ruby trunk
Merge branch 'backport-ruby-trunk'
added 2.1.0 for travis
	* ext/psych/lib/psych/visitors/yaml_tree.rb: support dumping Encoding
	  objects.

	* ext/psych/lib/psych/visitors/to_ruby.rb: support loading Encoding
	  objects.

	* test/psych/test_encoding.rb: add test

	* ext/psych/lib/psych.rb: add version
backport from libyaml-1.1.6
Merge pull request #187 from tenderlove/libyaml-0.1.6

backport from libyaml-1.1.6
bumping up version
merge from ruby trunk
YAML::ENGINE was removed in [Bug #8344]
Revert "YAML::ENGINE was removed in [Bug #8344]"

This reverts commit fa6aac2ab19762775fba78c264159efb4fcf3ecf.
* ext/psych/lib/psych/visitors/yaml_tree.rb: dump empty symbols with a
  tag so that they can be parsed on input. [Bug #9873] [ruby-core:62825]
* test/psych/test_symbol.rb: test for change