adding jscad sample file

samples/JavaScript/logo.jscad

@@ -0,0 +1,19 @@
+// title      : OpenJSCAD.org Logo
+// author     : Rene K. Mueller
+// license    : MIT License
+// revision   : 0.003
+// tags       : Logo,Intersection,Sphere,Cube
+// file       : logo.jscad
+
+function main() {
+   return union(
+      difference(
+         cube({size: 3, center: true}),
+         sphere({r:2, center: true})
+      ),
+      intersection(
+          sphere({r: 1.3, center: true}),
+          cube({size: 2.1, center: true})
+      )
+   ).translate([0,0,1.5]).scale(10);
+}