Rename SurfaceMesh::flipNormals to SurfaceMesh::reverse, or SurfaceMesh::reverseWinding

Simple change, reminder for later. The issue with flip normals is that it doesn't actually flip normals. It reverses windings.

In fact if you have per vertex normals defined and call flipNormals, expecting the normals to flip. It does nothing. Because again, it doesn't flip normals, it reverses windings. Two very different things.