Added a marching cubes algorithm to retreive normals induced by occupied/free voxels surrounding a given voxel.
Added an example on how to use the function.
Changed the include gard
Changed the signature of the function to use std::vector instead of
point3d*
Changed the example to use std::vector
Changed the return value to true and false instead of an int.
Merge pull request #27 from fmder/devel

Added a marching cubes algorithm to retreive normals