Allow URLs without any extension

[ThomasVille]

Fixes #33.

When make_meta_uri is called, if the URL ends with an extension, injects the .meta extension to it. If not, then return an error because we can't assume we can add an extension to a URL that didn't have one.

[johanhelsing]

Thanks

Hmmm.... What would be the downside of just always adding .meta instead, even if there is no extension?

[ThomasVille]

@johanhelsing I was thinking that if there's no extension in the original URL, then adding one doesn't make sense because the URL might end with something else than a file name.

For instance, if the glTF file is returned by a REST API like this:

https://example.com/api/gltf/8972016938af456cb3f8199e63a8673f016251/export

Then it doesn't make sense to send a query to:

https://example.com/api/gltf/8972016938af456cb3f8199e63a8673f016251/export.meta

This is basically the use-case I'm wanting to cover.

If you think we should send the query to .meta anyway then I can update my PR.

[johanhelsing]

I think it's ok like that. We can reevaluate later if someone has a use cause where we still would like to look for meta files.

[johanhelsing]

Thanks ❤️