Battery: add an opescad representation of the phone battery

This can be used to power the phone from a lab supply.
Signed-off-by: Angus Ainslie <angus@akkea.ca>

Battery/battery.scad

+$fn=30;
+
+center_hole=1;
+
+module cutouts() {
+    /* center hole */
+    translate([1,3.5,1]) 
+        cube([55,46,11], false);
+    translate([1,2.5,2]) 
+        cube([55,46,11], false);
+
+    if ( center_hole )
+        translate([3.5,5.5,-1]) 
+            cube([50,40,11], false);
+    
+    /* hold downs */
+    cube([5,2.5,1.6], false);  
+    translate([52,0,0])
+       cube([5,2.5,1.6], false);
+    
+    /* electrical connections */
+    translate([34,-0.5,1.5]) 
+        cube([2.5,1,6.5], false);
+    translate([37,-0.5,1.5]) 
+        cube([2.5,1,6.5], false);
+    translate([40,-0.5,1.5]) 
+        cube([2.5,1,6.5], false);
+
+    /* wire guides */
+    translate([35.25,0.5,1.5]) 
+        cylinder(6.5, d=1, true);
+    translate([38.25,0.5,1.5]) 
+        cylinder(6.5, d=1, true);
+    translate([41.25,0.5,1.5]) 
+        cylinder(6.5, d=1, true);
+    translate([35.25,0.5,2])
+        rotate([-90,0,0])
+            cylinder(6.5, d=1, true);
+    translate([38.25,0.5,2])
+        rotate([-90,0,0])
+            cylinder(6.5, d=1, true);
+    translate([41.25,0.5,2])
+        rotate([-90,0,0])
+            cylinder(6.5, d=1, true);
+    translate([35.25,0.5,7.5])
+        rotate([-90,0,0])
+            cylinder(6.5, d=1, true);
+    translate([38.25,0.5,7.5])
+        rotate([-90,0,0])
+            cylinder(6.5, d=1, true);
+    translate([41.25,0.5,7.5])
+        rotate([-90,0,0])
+            cylinder(6.5, d=1, true);
+};
+
+difference() {
+    cube([57,51,10], false);
+    cutouts();
+};