feature: Simple type-declaration statements

[qianxi0410]

As simplification of var declaration，Can you consider adding type declarations to the ranks of simplification?

exp:

type ExampleArgs struct {
	X int
}
type ExampleReply struct {
	Y int
}

after:

type (
	ExampleArgs struct {
		X int
	}
	ExampleReply struct {
		Y int
	}
)

[mvdan]

Nice catch - we have always meant to do this reformatting, but we didn't because of a bug when it comes to multi-line type declarations. I have a patch in progress locally.