By Simon Thomson Today is Waitangi Day, the national day of Aotearoa-New Zealand. It commemorates the signing of the Treaty of Waitangi, an 1840 agreement between native Māori and representatives of the British Crown, which is widely regarded as the founding document of the modern state. In New Zealand itself, the day has a rather sombre tone. Although it has been a public holiday for half a century, there are no celebrations or joyful displays of national unity. Instead, there is a sober commemoration ceremony at the site of the original signing, reflections on colonial history, and protests …