samples: add Terra samples

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

samples/Terra/emptystruct.t

@@ -0,0 +1,30 @@
+terra f(x :  {})
+	return x
+end
+
+print(f({}))
+
+terra f2(x :  {})
+	return x,x
+end
+
+print(f2({}))
+
+terra f3(x : {}, a : int)
+	return a + 1
+end
+
+assert(f3({},3) == 4)
+
+terra f4(x :  {})
+	return x,4
+end
+
+a = f4({})
+assert(a._1 == 4)
+
+terra f5()
+	return f({})
+end
+
+f5()