Versioning Strategy

[titzer]

There have recently been a number of issues cropping up around versioning Wasm modules and I think we need to discuss them in a holistic fashion.

In particular, it seems like we could be better on several fronts.

• Wasm 1.0 (MVP), yearly releases (see Require implementations, in order to be compliant, to be able to constrain to the actual spec spec#1428)
• WebAssembly profiles, consisting of feature sets (Couldn't find a reference for this, but @rossberg has been working on this)
• Feature detection (https://github.com/webassembly/feature-detection)
• Ecosystem alignment of supported features

In general, I think we should have a broader discussion about WebAssembly versioning encompassing all these aspects.

Let's use this issue to discuss pain points and requirements.

[sbc100]

Regarding producers, we have discussion over on tooling conventions about if/when to enable a given feature by default: WebAssembly/tool-conventions#158.

The goal would be for tools to align on the same defaults, and I'm sure this discussion here will help inform what those defaults should be.