Produce new pre-release version that support 2.4/develop

[per-samuelsson]

Use appropriate branches (master = 2.3, develop = develop/2.4).

[per-samuelsson]

At the end: update the reference from develop => new package version.

[per-samuelsson]

This thing called the Visual Studio Marketplace was a different beast. There, extensions can be versioned, but you can only host one version of an extension (i.e "latest"), meaning we can't have both 2.3 and 2.4 compatible extensions under the same name.

For the moment, I'll just let it be, having the one I just pushed as the only one - it correspond to Starcounter RC (and is backwards-compatible with 2.2).

On NuGet, I'm publishing parallel packages of both though, so our code can bring down the correct one and bundle it.

[per-samuelsson]

Done. Merged and pushed in 6d68e13.