switch off postition tracking by default
switch off postition tracking by default

contary to what sax.js Readme claims [position tracking is on by
default][1]
this change sets it to `false` to revert to our pre 1.2.0 defaults

see: issacs/sax-js#174

[1]: https://github.com/isaacs/sax-js/issues/174

code42day/sax-stream