Files with .so extension are ignored.
* ext/psych/psych.c: move path2class and build_exception methods
  from psych_to_ruby.c.
* lib/psych/core_ext/: Add missing core classes and swtich to new_with.
Add Psych::Binary class, acts as factory.
Add Psych::Boolean class, acts as factory.
Add legacy Syck schema (only has tags that are not in Ruby schema).
Remove swap file, however it got in there.
test/psych/: Tests additions and adjustments

* A few tests changed to adjust for modified behavior.
* Add some additional tests.
* Add some TODO items to revist.
Add scanner option to Coder.
lib/psych/core_ext.rb: Add new core_ext requires.
lib/psych/visitors/yaml_tree.rb: Add schema option.
Use new_with for Omap and Set.
lib/psych/visitors/visitor.rb: Remove stumpy comment.
Use Coder design, and polish schemas.
Keep as much of deprecated.rb working as possible.
Refine schema.rb code, noting worry about tag order for precedence.
lib/psych.rb:

* Fix options on load_file/_stream.
* Route legacy type defs to @global_schema.