schema and yaml: correct bugs in schema and use safe YAML load/dump
* schema: rename some "id" values, and fix a major bug where the value of "items" was given as an array of one JSON schema, thereby only validating the first element of a list instead of *all* elements in the list.
* testsuite: fix test data to match newly corrected schema.
* yaml: always use SafeLoader and SafeDumper or preferably the corresponding LibYAML classes if installed.
* yaml: simplify validation of parser errors by catching a generic Exception rather than yaml.parser.ParserError and IOError, also now implicitly catching a yaml.constructor.ConstructorError caused by the presence of "!!python/unicode" tags.
* version: bump to 0.1.16.
Signed-off-by: Graeme Watt <graeme.wattdurham.ac.uk>