samples: add Terra samples

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

samples/Terra/nestedcalls.t

@@ -0,0 +1,11 @@
+
+terra foo3(a : &int) : &int
+  return a
+end
+
+terra bar2(a : int)
+  return @(foo3(&a))
+end
+
+local test = require("test")
+test.eq(bar2(42),42)