add raw vertex input in devel mode. stub in slice connect shadow test for performance over plain face union

src/geo/slicer.js

@@ -828,7 +828,8 @@ function removeDuplicateLines(lines) {
 gapp.overlay(base, {
     slice,
     sliceZ,
-    slicePost: {}
+    slicePost: {},
+    sliceConnect
 });
 
 });