Summary

Make textlint preset more casual

UseCase

The user use preset-x and rule-a.
preset-x contain rule-a, but also use rule-a.

{
    "rules": {
        "preset-x": {
            // other many rules
            // ...
            "rule-a": true
        },
        "rule-a": true
    }
}

In the case, rule-a's error always is duplicated.

The user not want to see duplicated messages.

Soluction A

The user disable "rule-a" in the preset.

{
    "rules": {
        "preset-x": {
            // other many rules
            // ...
            "rule-a": false
        },
        "rule-a": true
    }
}

Soluction B

textlint ignore duplicated messages.

The above case is rare in current.
But incresing custom preset, this case will not be rare.

Proposal

Duplicated messages is ignored by default.

Duplicated messages is that have same range and same message.
(Not depended on ruleId. ruleId is flexible property)