YAML: cleanup, tags are defined in the ffi
YAML: ffi typo cleanup
YAML: ffi, fix default tags
YAML: don't test types on complex key test
YAML: use factor's c-string in more places
YAML: fix parsing when key is f
YAML: add a debug vocab
YAML: add a debug word to check sizes of structs
YAML: declare function parameters as bools
YAML: add some tests from pyyaml test suite.
YAML: convert some factor types to/from yaml types
YAML: cleanup USING: