feat(axis): Intent to ship axis.evalTextSize

[netil]

Issue

#3889

Details

Implement axis text's size evaluation option.

New axis.evalTextSize option has three different usage options.

axis: {
    // 1: default, which will memoize evaluated axis text size
    evalTextSize: true,

    // 2: will evaluate the dimension of axis text size every time.
    evalTextSize: false,

    // 3: customize dimension evaluator
    evalTextSize: function(text) {
        ...
        return {width, height):
   }
}

[coveralls]

coverage: 94.215% (+0.002%) from 94.213%
when pulling 28ae3e8 on netil:axis#3889
into 9c668e6 on naver:master.