samples: add Terra samples

source: https://github.com/zdevito/terra/tree/master/tests

samples/Terra/forlist.t

@@ -0,0 +1,24 @@
+
+
+struct Range {
+    a : int;
+    b : int;
+}
+Range.metamethods.__for = function(syms,iter,body)
+    return syms, quote
+        var it = iter
+        for [syms[1]] = it.a,it.b do
+            body
+        end
+    end
+end
+
+terra foo()
+    var a = 0
+    for i in Range {0,10} do
+        a = a + i
+    end
+    return a
+end
+
+assert(foo() == 10*9/2)