samples: add Terra samples

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

samples/Terra/overloadmethod2.t

@@ -0,0 +1,17 @@
+
+struct A { a : int }
+A.methods.foo = terra(self : A, a : int)
+	return self.a + a
+end
+
+terra A:foo() 
+	return self.a
+end
+
+
+terra doit()
+	var a = A { 3 }
+	return a:foo() + a:foo(1)
+end
+local test = require("test")
+test.eq(doit(),7)