Substitute datepicker for pre-HTML5 browsers

Live Demo Here

This commit is the improved datepicker based on the original from Corion.net.

This improved version:

• attaches to fields if the current browser does not have native support for date inputs.
• modifies webkit native date inputs with CSS to work more logically and be slightly less ugly (if native input is available).
• contains an extensive UI rework to simulate the Firefox 57 native datepicker.
• detects focus loss and hides the datepicker automatically.
• contains fixes and workarounds for all manner of inconsistent behaviour on legacy browsers:
  • supported on IE 6 - 11, Firefox 3.6 (manual attachment) - Firefox 56 (auto attachment), and Chrome 19.
• uses YYYY-MM-DD ISO format for compatibility with HTML5 native date inputs.
• and has many more improvements....

Live Demo Here

As the original author simply states "Artistic License", due to release dates it is assumed that the Artistic License 1.0 is the applicable license.