Let layers be strings.

[rodrigogiraoserrao]

Motivated by syntax highlighting of TCSS, I'd like us to consider allowing the values of layer and layers be strings.
I.e., allow CSS like this:

Screen {
    layers: "layer-name";
}

#widget {
    layer: "layer-name";
}

Nothing needs to be done for layer because it doesn't check its token type.
For layers, the change is trivial and can be seen in this PR.

[willmcgugan]

Seems reasonable. Could you add a changelog entry?

[rodrigogiraoserrao]

Seems reasonable.

Just to confirm: seems reasonable that we accept strings and push it as the "standard" or just that we have this possibility?

[willmcgugan]

I think strings are only necessary if you want additional characters or spaces in your layer names. I wouldn't say it should be the standard exactly, just an alternative.

[rodrigogiraoserrao]

I think strings are only necessary if you want additional characters or spaces in your layer names. I wouldn't say it should be the standard exactly, just an alternative.

Understood.

Feel free to review to approve/reject.