Datepicker year selector

[jkruder]

Added capability to select a year by tapping on the year of the date in the date picker (similar in functionality to http://david-mulder.github.io/polymer-docs/bower_components/paper-date-picker/demo.html (page is a bit slow to load). Can also use 'quick year' change buttons in the calendar toolbar; I wanted to provide a user interaction that was similar to changing months. The toolbar year change icons can be hidden but you will need to 'opt-out'. Thoughts on that? The year change toolbar buttons can be easily backed out. Year selection satisfies #191.

Can also provide a date range for valid dates; this satisfies mui/mui-x#7543. Also added capability to disable individual days by providing a function that returns true to disable and false otherwise:

<DatePicker shouldDisableDate={myDateControlFunc} />

The docs date-picker page has been updated with a ranged date picker example.

[jkruder]

@mmrtnz I was thinking about using the clone method (React 0.13) for some refactoring of #442 into the css-in-js branch to support pseduo selectors like first-child and last-child.

firstChild(children, style) {
  var [firstChild, otherChildren] = children;
  var newChild
  newChild = React.cloneElement(firstChild, {style: style});
  return otherChildren.unshift(newChild);
}

For selectors like before I envision wrapping each element in a div and inserting the before content. Something like:

before(children, beforeElement) {
  return React.Children.map(children, function(element) {
    <div>
        {beforeElement}
        {element}
    </div>
  });

}

If we want to specify a before for each child element, we can check beforeElement's type and treat it as a one-to-one array with children or if it's a React element use it for all children.

What do you think? I don't want to go too far down this road...I did first/last child wrapping for the toolbar and it looks the same as it does without.

[mmrtnz]

That seems like a much cleaner approach to our current brute-force solution to :first-child and :last-child. If the toolbar looks the same with or without first/child wrapping, I would prefer to do without. I've been striving to use as little pseudo-selectors possible, because managing too many pseudo-selectors only complicates the component in my opinion.

There exist a BeforeAfterWrapper component that does what you've described. It contains some comments detailing its usage. Clearfix is an example for using BeforeAfterWrapper. Maybe you can test to see if it works as well as your current approach?

[jkruder]

@mmrtnz Toolbars display the same without the brute-force prop setting so I've removed it in my branch. I agree with your comment on pseudo selectors; I'll try to remove as much as I can from my date picker changes.

The only difference between what already exists and what I proposed is component vs utility. I wont need a before/after solution for these date picker changes but I may for the time picker that I've been working on.

I should have these changes up soon.

[jkruder]

See #511