InputNumber internationalization

[VincentBerthier]

In some languages, the decimal separator is not the . (in French for example, it’s the ,).

As it is, even with the page in French, in an InputNumber the separator remains the . at least when inputting new values because the display replaces that with a , (at least sometimes, it’s weird).

Still, it would be good if we could allow custom seperators at least for inputs. I’ve tried to do that but without success (even if the parsing works, it gets messed up when displaying it back).