Add missing mint type conversions

[stefnotch]

We're planning to use ultraviolet together with https://github.com/LPGhatguy/crevice (turns Rusty structs into structs that the GPU understands).

This adds more mint types to Ultraviolet, which will then make it possible to add really nice ultraviolet support to crevice.

[fu5ha]

Nice! Can you add an entry to the changelog? :)

[stefnotch]

Gladly, changelog entry has been added

[stefnotch]

Nice, glad to see that this got merged.

Any super rough estimate for when the next release is going to come around? (e.g. Sometime this month? Or within the next 6 months? Or no concrete plan yet?) I'm mainly asking so that my team-partner and I can update upstream libraries and contribute more niceness to the lovely Rust ecosystem.

[fu5ha]

Probably a month or two? Really just depends on whether other contributions come along and whether I think about it haha. Also if anyone really wants a release I'm usually fine with just cutting one, the stability guarantees and release cadence here are pretty lax still.