Run suite tests with file locations, not an IO.
Fix problems with RSpec in suite_helper.
If processingMode is json-ld-1.0, always output comacted output using content of provided context, not just a reference to the context.
Change ProcessingError to JsonLdError to match spec. Use @code with accessor, rather than @base_message, still comes out in message.
Change default for useNativeTypes to false.
Remove context parameter from toRdf; now uses :expandContext option.
Make sure base found for input document is preserved as default base in context for subsequent steps.