Codechange: Increase scrollbar length limit to 32bits

[LordAro]

Also makes scrollbar internals properly use unsigned numbers. Bumped scrollbar limit to uint(32) as well, because why not

Fixes #7613

[stormcone]

There are 3 occurrences of this->group_sb->SetCount((uint)this->groups.size()); in group_gui.cpp, where I think the (uint) could be removed.

[LordAro]

good catch, seems I'd missed quite a few

[TrueBrain]

No longer crashes the game, tried a few windows, scrolling seems to work fine.

I am just there will be some window that doesn't work as we want or what-ever, but we will fix that when people report it :D

[LordAro]

Shouldn't be merged yet, lots of size_t -> uint warnings on Windows. Going to have to readd a load of casts :(

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[LordAro]

I've updated it to just increase the size, no fiddling around with type-signedness.

...Except for some reason changing it from unsigned short to unsigned int has caused the compiler to no longer be able to make as many coersions as it was able to previously. I've fixed them in a "minimal" way. A better solution would be to go through the whole system to check everything for over/underflows, as I've no doubt there are some lurking somewhere.

[nielsmh]

This code has a lot of typecasting to stop the compiler complaining about signed/unsigned type ranges, but it's not actually range safe as far as I can tell. If the scrollbar isn't going to work properly with more than 2^31 elements in the list anyway, just make it use a plain signed int type and do some sanity checks against negative numbers in a few strategic locations.

[nielsmh]

This line is really confusing. Actually I'm not sure why Scrollbar::SetPosition assert-checks that the parameter is in range, instead of just clamping it into range itself. Letting the scrollbar handle that would make all the using code simpler, wouldn't it?