feat: replaced mathematical kwargs in scheduler constructors

[lfenzo]

Closes #41.

For cyclic schedulers, I've replaced λ* with l*, but I'm open to suggestions. At this moment I preferred replacing only the symbols instead of making more drastic changes to the API. Tests and docs were also adapted!

cc.: @darsnack

[lfenzo]

Good to go?

[darsnack]

I'm happy with your chosen naming scheme, and most of the changes here are broadly good to go.

I would prefer to release a patch with deprecations first. Can we do something like this:

function depkwargs(fn::Symbol, kwargs, remaps::Pair...)
    remaps = Dict(remaps...)
    kwargs = map(keys(kwargs)) do kw
        if haskey(remaps, kw)
            Base.depwarn("Keyword $kw is deprecated. Replacing with $(remaps[kw]) instead.", fn)
            return remaps[kw] => kwargs[kw]
        else
            return kw => kwargs[kw]
        end
    end

    return (; kwargs...)
end

function Triangle(; kwargs...)
     kwargs = depkwargs(:Triangle, kwargs, :λ0 => :l0, :λ1 => :l1)
     return Triangle(kwargs.l0, kwargs.l1, kwargs.period)
end

[lfenzo]

function depkwargs(fn::Symbol, kwargs, remaps::Pair...) (..) end

Very clever! Added to all constructors modified in this PR. Thanks for the snippet!

[darsnack]

One more small change and then we are good to go. Can you also bump the patch version?

[darsnack]

Looks good, thank you! The nightly failure is unrelated to the PR.

[lfenzo]

I'm still trying to figure out what happened here, as it turns out, my force push after a git reset to revert the formatting in docs/make.jl somehow caused this PR to be closed.

The body of _tridecay2 and its variants were transferred to the respective positional constructors; patch number was updated and CI errors with Julia nightly seem unrelated.