samples: add Terra samples

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

samples/Terra/overload.t

@@ -0,0 +1,17 @@
+
+terra foo(a : int)
+	return 1
+end
+
+terra foo(a : &int8)
+	return 2
+end
+
+print(#foo.definitions)
+
+terra doit()
+	return foo(1) + foo("what")
+end
+
+local test = require("test")
+test.eq(doit(),3)