minor release

The unitmacro \number had some collision with other packages. The unitless unit has been renamed from \number to \unitless. The declaration in the Latex preamble \DeclareSIUnit\number{} has therefore to be replaced with \DeclareSIUnit\unitless{}.

The parsing of uncertainty values in the package siunitx has changed. It was incompatible with the output of Number.__tostring(). To mitigate this issue a new method Number.tosiunitx() has been added.