Everything which can emit a parse error should have the error handler
and data stream as properties and use the ParseErrorEmitter trait to
avoid complicating the task of actually producing an error.
Normally the Parser would be expected to set the error handler before it
begins (this commit does not do this) and unset it after it's done.
Alternatively, the entire means of reporting errors can now be easily
replaced.
• Fixed bug where Data::consumeWhile and Data::consumeUntil wouldn't move the pointer back one position if there were no matches.
• Changed DataStream to Data.
• Made each class have its own debug static property so each can print debug information separately.
