added shape_ellipse

src/shape_ellipse.scad

@@ -0,0 +1,16 @@
+function shape_ellipse(axes) =
+    let(
+        frags = $fn > 0 ? 
+            ($fn >= 3 ? $fn : 3) : 
+            max(min(360 / $fa, axes[0] * 6.28318 / $fs), 5),
+        step_a = 360 / frags,
+        shape_pts = [
+            for(a = [0:step_a:360 - step_a]) 
+                [axes[0] * cos(a), axes[1] * sin(a)]
+        ],
+        triangles = [for(i = [1:len(shape_pts) - 2]) [0, i, i + 1]]
+    )
+    [
+        shape_pts,
+        triangles
+    ];