Added ability for user to define minimum and maximum return thresholds.  Values returned outside these thresholds will be discarded.

Fixed an issue where the rotation angle returned from the HDL might be 36000 (instead of 0).  This causes a buffer access overflow.
Merge pull request #20 from KevenRing/master

Min/Max Value Threshold for sensor.  This also addresses an issue with azimuth angles from the sensor.