feature-request: Initialize struct instance command

[josephbuchma]

It would be nice to have something like :GoInitStruct.

Proposed workflow.

Consider we have this struct:

type Car struct {
    Name string
    Color string
    Weight int
}

And when I create instance of it

car := &Car{}

I place a cursor at Car{} and run :GoInitStruct, which converts the code to:

car := &Car{
    Name: "",
    Color: "",
    Weight: 0,
}

[ideally] it also moves cursor to the first field value assignment [where I can start editing it immediately], and when I press Tab (for example), it moves cursor to next field assignment.

[fatih]

There is a tool already for this. I've talked with @davidrjenni back in GopherCon to implement something like this. Happy for us he did it with https://github.com/davidrjenni/reftools/tree/master/cmd/fillstruct all we need is to integrate into vim-go.