[Feature] built-in and direct support of error bar

[feixyz10]

What problem does this feature solve?

currently error bar can only be realized by drawing three line (two horizontal and one vertical), like the official examples like this. This is very indirect and inconvenient. Considering that error bar is used in data visualization very commonly. So is it possible to add 'errorbar' type to directly support errorbar functionality?

What does the proposed API look like?

series: [ { data: [[6, 7], [5.9], ..., [lower bound, upper bound]], type: 'errorbar' } ]