adds range_max param

Sets the point cloud (PC) and depth images value to range_max when the
depth is 0.0 (and < cutoff), since it comes from the far (no) reading.

If range_max == 0.0 we set bad_point (depth image) or NaN (PC) as
before.
cosmetics
Merge pull request #2 from efernandez/range_max

Range max