Support for parsing progress

[peterpp]

JsonStreamingParser is able to report progress of file parsing. It will be really handful to have this progress, because processing of large file can take a lot of time.

The only what you need is to add function "filePosition" to your Listener and add propagate progress values to callback (or add another callback).

[MAXakaWIZARD]

@peterpp Sorry for such a long silence, I will try to implement this soon.

[MAXakaWIZARD]

@peterpp Currently all that parser can do - just pass lineNumber and charNumber. We can't even calculate progress percentage. Any thoughts on how line numbers and/or char numbers can be helpful?

[p1ratrulezzz]

Just had to implement this in p1ratrulezzz@b6c1563#diff-1041b02aae148a89853dc0d2710afc9cR194

At least it works with files, maybe can be helpful