Replace Enumerable.Count(list) with list.Count

[SokyranTheDragon]

Minor change that should not really affect anything, as Enumerable.Count() would still end up calling list.Count:

switch (source)
{
    // Skipped irrelevant code
    case ICollection<TSource> sources:
        return sources.Count;
    // Skipped irrelevant code
}

[SokyranTheDragon]

Merged with master, now targeting 1.5

[notfood]

Don't merge, rebase. Look at the changes, this is not merge-able anymore.
https://www.atlassian.com/git/tutorials/merging-vs-rebasing

[SokyranTheDragon]

Welp, guess I should get to it. I guess I should learn more about Git. I've honestly never looked into how rebasing works, since merging usually for me good enough.

[SokyranTheDragon]

@notfood did I do it correctly here and in #432? I've force pushed to get rid of the merge commit, as the changes due to rebase ended up being rejected otherwise.

[notfood]

Looks correct now. Usually just look at the diff, if it contains things you didn't intend to add, some wrong commit sneaked in