all or none range ,- feature request

[mkhanal]

Feature request - all or none range.

Intention:
When used as a range mode, the intention is to get a range of date. Getting only one value holds almost no value (for most cases).

Right now the component allows selection of only start date and apply. It would be better to restrict user (maybe with flag like bothDatesMandatory) to disable apply button till both start and end range are specified.

eg:

<range-date-picker :bothDatesMandatory="true"></range-date-picker>