wheeheee

I would like to rebase then merge this PR after #502, since it has gotten a little big, and I think it's easier to rebase conflicting PRs one by one...

> Have you benchmarked whether the `@inline`s you have added are actually beneficial? Yes, I have them [here](https://github.com/JuliaDSP/DSP.jl/pull/541#issuecomment-1956573592). Not zeroing doesn't help as much as the inlining, maybe about a...

On the topic of abstract supertypes, `Filter` doesn't seem to be doing anything

With so many configs lying around, would it be good to also add configs for `Periodogram` and `Periodogram2`? I mean, not in this PR, of course.

```julia julia> versioninfo() Julia Version 1.10.0-rc2 Commit dbb9c46795 (2023-12-03 15:25 UTC) Build Info: Official https://julialang.org/ release Platform Info: OS: Windows (x86_64-w64-mingw32) CPU: 8 × 11th Gen Intel(R) Core(TM) i5-1135G7 @...

Hm, maybe I didn't clear everything. Just to confirm, the cache is in ~/.config/Code/User/globalStorage or its equivalent in Windows, right? Also, I have the VSCode setting `"julia.symbolCacheDownload": false` because of...

I hope enabling local caching is still supported behaviour? 🤞 Although there are still missing methods if it's not.

Also I think it's a JuliaHub only issue, the buttons to the docs on the GitHub README are fine, so you can refer to those.

Should `tdconv` be exported just like `tdfilt`? Then users could more easily choose the cutoff themselves.

I kind of like the names `tdconv` and `fdconv`, but maybe adding a kwarg is better, since people might also want to choose the overlap-save algorithm and that's one more...