Schema: Do not implicitly match "v"-prefixed versions for tags: true releases

[FichteFoll]

As came up in wbond/packagecontrol.io#41, the implicit matching of v-prefixed releases is more of a mis-feature caused by the lack of the tag-prefix-select feature in schema 2.0 which was only added in 3.0.0. Since this is now possible, tags: true should explicitly match only versions without any prefix.

Migrating the default channel would work as follows: All packages specifying tags: true need to be checked whether the v prefix is matched or not (for the highest version). If it is, the release needs to be changed to tags: "v".

Unfortunately this change is forwards incompatible (: breaking) and we missed the 3.0.0 train, so 4.0.0 would be necessary.

[FichteFoll]

With how long this has been in action, I don't see a reasonable way forward to address this. It's not hugely important to me, anyway, so I'm retracting this feature request.