Add the copy kwarg

BooleanImage:
If you pass in np.bool data and say don't copy, then this will
be honoured. However, if you pass non-np.bool data, then we have
to make a copy, and then we raise a warning to tell you!
Raise a warning if we copy data in image

Also add some tests to check this
Write new sanity tests!
Warnings raised in trimesh/pointcloud
Add tests for pointcloud copying

Add trimesh tests
Add the copy kwarg to landmarks

Also, try not to copy the target when setting a landmark group!
Comment where function should be used
Merge pull request #343 from patricksnape/copy_kwarg

Copy kwarg