Initialize curvature in PointNormal default constructor

[SergioRAgostinho]

Fixes #2658

[taketwo]

Well... the thing is that the data is sort of initialized. When cloud.resize() is invoked, it is calling the resize method of an STL vector.

You are right, good catch.

I'm not sure if we need to initialize padding floats in curvature (data_c). In coordinates and normals we do that because they can be used as homogeneous vectors (getVector4fMap()) and thus the last component should be 1/0 to ensure proper application of transforms. But we don't do anything like this with curvature data, so there is no reason to care about the contents of the padding bytes.

[SergioRAgostinho]