Track position in file

This patch enables position tracking of JSON file that is parsed: line and character number. `JsonStreamingParser_Listener` interface is extended, error messages are contain position of error.

This allows to check JSON file in a specific way and accurately report place of mistake. I use it to validate [ICU](http://site.icu-project.org/) messages before writing them to the translations database.

If you'll accept this enhancement, better to tag current version as 1.0.0 before merging, because this patch breaks back compatibility.