Cleanup: vertex coordinate access, naming & minor changes

This also splits vertex access and allocation so it's possible
to copy coordinates into an existing array without allocating it.

source/blender/modifiers/intern/MOD_surface.c

@@ -130,7 +130,7 @@ static void deformVerts(ModifierData *md,
     float *vec;
     MVert *x, *v;
 
-    BKE_mesh_apply_vert_coords(surmd->mesh, vertexCos);
+    BKE_mesh_vert_coords_apply(surmd->mesh, vertexCos);
     BKE_mesh_calc_normals(surmd->mesh);
 
     numverts = surmd->mesh->totvert;