minor changes with long descriptions:
FLARSingle/MultiMarkerDetector.setAreaRange() should refer directly to default values in FLARLabeling. changes to allow this:
- made FLARLabeling.AR_AREA_MAX/MIN constants public
- set FLARLabeling.AR_AREA_MAX/MIN as default values for parameters to FLARSingle/MultiMarkerDetector.setAreaRange()
also, added code to FLARMultiMarkerDetector.detectMarkerLite() that allows FLARToolkit's internal thresholding algorithm to be skipped, so developers can implement their own thresholding algorithms.