add lisp packages

lisp/yasnippet-snippets/snippets/c++-mode/operator!=

@@ -0,0 +1,9 @@
+# -*- mode: snippet -*-
+# name: operator!=
+# key: !=
+# group: operator overloading
+# --
+bool ${1:Name}::operator!=(const $1 &other) const
+{
+    return !(*this == other);
+}