samples: add Terra samples

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

samples/Terra/eager.t

@@ -0,0 +1,10 @@
+
+
+local fn = terra() return 0 end
+
+for i = 1,10 do
+	fn = terra() return fn() + 1 end
+end
+
+local test = require("test")
+test.eq(fn(),10)