samples: add Terra samples

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

samples/Terra/macro3.t

@@ -0,0 +1,14 @@
+
+
+foo = macro(function()
+	local terra bar()
+		return 3
+	end
+	return bar
+end)
+
+terra baz()
+	return foo()()
+end
+
+assert(baz() == 3)