#107 XeTeX, harfbuzz and unicode normalisation

[Maïeul Rouquette]

As Harfbuzz makes its own unicode normalization, the \XeTeXinputnormalization has no (or not full) same effect. See this message http://tex.stackexchange.com/q/229044/7712.

I thinks it should be indicated in the handbook of XeTeX.