build error by auto-generated file imported and not used: "strconv"

[shota-takahashi-tg]

Hello,
Thank you a lot for this package. It will be a great help to our Japanese full-text search function.

By the way, I encountered a problem as the title of this issue when I start to use this (latest version 812be11 ).
I only tried to autogen one struct as below:

// +smg
type ChatLog struct {
	ApplicantID string    `search:",string"`
	Body        string    `search:",ngram"`
	Created     time.Time `search:",unixtime"`
}

I checked into codes and this line seem to cause this.
https://github.com/favclip/smg/blob/master/generator.go#L82

thanks again

[shota-takahashi-tg]

I succeeded to avoid this for now by editing struct as below:

// +smg
type ChatLog struct {
	ID          int       `search:",id"`
	DSKeyJSON   string    `search:"-"`
	ApplicantID string    `search:",string"`
	Body        string    `search:",ngram"`
	Created     time.Time `search:",rank"`
}

[shota-takahashi-tg]

Now I've found that the struct definition below causes this:

ApplicantID string    `search:",string"`

string Tag is applicable only to int field

I think it would be better that autogen fails when such definition is set.

Thanks.