Better ziptie model.

Better cable_tie using zipties.
Added cable ties to ssr_shroud_fastened_assembly().
Added test and documentation for wire.scad.

tests/wire.scad

@@ -0,0 +1,82 @@
+//
+// NopSCADlib Copyright Chris Palmer 2018
+// nop.head@gmail.com
+// hydraraptor.blogspot.com
+//
+// This file is part of NopSCADlib.
+//
+// NopSCADlib is free software: you can redistribute it and/or modify it under the terms of the
+// GNU General Public License as published by the Free Software Foundation, either version 3 of
+// the License, or (at your option) any later version.
+//
+// NopSCADlib is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+// without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+// See the GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along with NopSCADlib.
+// If not, see <https://www.gnu.org/licenses/>.
+//
+include <../core.scad>
+
+include <../vitamins/wire.scad>
+
+bundle = [7, 1.4];
+
+bundle_r = cable_radius(bundle);
+
+thickness = 2;
+w = 50;
+d = 20;
+h = 40;
+wire_l = 90;
+
+module wires() {
+    translate_z(bundle_r)
+        rotate([0, 90, 0]) {
+            n = cable_wires(bundle);
+            d = cable_wire_size(bundle);
+            if(n > 6)
+                color("green") {
+                    cylinder(d = d, h = wire_l, center = true);
+                    wire("green", 7, wire_l);
+                }
+
+            m = n > 6 ? n - 1 : n;
+            for(i = [0 : m - 1])
+                rotate(i * 360 / m)
+                    translate([bundle_r - d / 2, 0]) {
+                        colour = ["black", "brown", "red", "orange", "yellow", "blue", "purple"][i];
+                        wire(colour, 7, wire_l);
+                        color(colour)
+                            cylinder(d = d, h = wire_l, center = true);
+                   }
+
+            %cylinder(r = bundle_r, h = wire_l - 10, center = true);
+        }
+
+    color(pp1_colour) {
+        rotate([90, 0, 90])
+            linear_extrude(height = thickness)
+                difference() {
+                    translate([-w / 2, 0])
+                        square([w, h]);
+
+                    mouse_hole(bundle, 0);
+                }
+
+        translate_z(-thickness)
+            linear_extrude(height = thickness)
+                difference() {
+                    translate([thickness -d, -w / 2])
+                        square([d, w]);
+
+                    translate([-15, 0])
+                        cable_tie_holes(bundle_r, 0);
+                }
+    }
+    translate([-15, 0])
+        cable_tie(bundle_r, thickness);
+}
+
+if($preview)
+    wires();