Define preferred estimation scale per project

[ConradGroth]

We use the plugin to estimate Fibonacci numbers, but this requires two additional clicks, because the default selected scale is "Planning Cards". Maybe some other project want to estimate t-shirt-sizes by default.

With PR #37 this really helpful plugin gets the possibility to store configuration about allowed projects. Maybe this configuration can be enhanced to save a preferred estimation scale per project.

[marcelfrank-dev]

Good suggestion 🤔

I will check what I can do there 👍

[aslafy-z]

I think there should be two options:

• A per-project option: Default Estimation Scale, if set, the scale is not asked before starting the round.
• A global option: Default Estimation Scale, if set, it becomes the default selected option when starting a round.