A stab at creating a themeable decorator

[ntgn81]

My stab at consolidating all theme stuff used in components into one place.

• HOC to wrap components to add muiTheme context, or default theme if context not given
• Components themselves, once wrapped, will receive muiTheme through props.muiTheme.

I tried to wrap DatePicker and it's immediate children - TextField, DatePicker

Issues:

• TextField uses StylePropable mixin
  • Updated StylePropable to consider this.props.muiTheme (not really an issue)
• DatePickerDialog exposes public methods (show, dismiss). HOC, in it's simplest form, hides them.
  • This makes clicking on DatePicker input not opening the Dialog, as the show method is being called through ref
  • I had to declare statics.publicMethods in DatePicker, and make the HOC proxy those methods through
  • This, I think, is a cool, unintended feature - declaring which methods are public - good for documentation.
• The problem I don't have good solution for is when the components are being accessed directly for it's properties ( do we have that case?). I see Dialog is accessing it's children directly for height and style, but they are React components, not MUI components.