Vue2-datepicker: [Feature] Adjust Z-Index of popups to account for Bootstrap modals

[camper2020]

Version 3.0.0+ of DatePicker does not _appear_ to show the popup on BS Modals. The popup does show but the z-index CSS property of .mx-datepicker-popup is set to 1000 which is behind BS Modal.

Could the default z-index be changed to 2000 to put it in front of these modals (and potentially other popups)

Marking this as a feature and not a bug, as there is nothing wrong with the DatePicker popup functionality and the CSS property can also be easily overridden in applications. Only suggesting it as it may cause confusion when the popup _appears_ to not show.

Thanks for making such a helpful component!

[mengxiong10]

Good advice

[digEmAll]

I second this request and I'd suggest to make the z-index a scss variable.

[mengxiong10]

v3.3.1