Increase the number of arguments accepted by UndoRedo methods

[groud]

I originally wanted to implement that using variadic templates/parameter packs, but all solutions I could find have significant drawbacks. I instead went the easy route by increasing the number of accepted arguments.

For the details about why variable arguments of the same types have drawback, see this: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1219r0.html

This blog also has 3 blog posts about the issue:
https://www.fluentcpp.com/2019/01/25/variadic-number-function-parameters-type/
https://www.fluentcpp.com/2019/01/29/how-to-define-a-variadic-number-of-arguments-of-the-same-type-part-2/
https://www.fluentcpp.com/2019/02/05/how-to-define-a-variadic-number-of-arguments-of-the-same-type-part-3/

[fire]

Looks good to me.

Not sure about unintended consequences, but I can't see anything wrong.

[akien-mga]

Thanks!