use c-style for loop

src/__private__/__reverse.scad

@@ -1,6 +1 @@
-function __reverse(vt) = 
-    let(to = len(vt) - 1)
-    [
-        for(i = [0:to])
-            vt[to - i]
-    ];
+function __reverse(vt) = [for(i = len(vt) - 1; i >= 0; i = i - 1) vt[i]];