split match by index and match by name

[suqin-haha]

struct {
    	T6 bool   `xyz:"first,first" want:"{\"Name\":\"first\",\"First\":true}"`
        T7 bool   `xyz:"first,!first" want:"{\"Name\":\"first\",\"First\":false}"`
}

fix delete(kv, value) will make second first never match.

ref: #22 (comment)

[muir]

Suggested change

	newElements := []string{}
	newElements := make([]string, 0, len(elements))

[muir]

Suggested change

	newElements := []string{}
	for i, e := range elements {
	if elementsConsumed[i] {
	continue
	}
	newElements = append(newElements, e)
	}
	newElements := []string{}
	for i, e := range elements {
	if elementsConsumed[i] {
	continue
	}
	newElements = append(newElements, e)
	}
	elements = newElements

just use this to filter elements, you don't need a new variable exposed to the rest of the function.

[muir]

I don't like the repeat call to Atoi. I'm not sure it can be avoided though.