samples: add Terra samples

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

samples/Terra/methodmissing.t

@@ -0,0 +1,17 @@
+
+
+struct A {
+	a : int
+}
+
+A.metamethods.__methodmissing = macro(function(methodname,obj,anarg)
+	print(methodname)
+	return `anarg + [string.byte(methodname,1,1)]
+end)
+
+terra foobar()
+	var a : A
+	return a:a(3) + a:b(4)
+end
+
+assert(foobar() == 202)