add count

docs/lib3x-count.md

@@ -0,0 +1,15 @@
+# count
+
+Returns the number of times `test` return `true` in the list.
+
+**Since:** 3.3
+
+## Parameters
+
+- `lt` : The list.
+- `test` : A testing function.
+
+## Examples
+
+    points = [[7, 2, 2], [1, 1, 2], [3, 4, 2], [3, 4, 2], [1, 2, 3]];
+    assert(count(points, function(p) norm(p) > 5) == 3);