v2.5.1

• Added styling when mouse hover at dates on the calendar on all available themes.
• Fixed #12 to enable fast month switching.
• Use new Date() to get total number of days in a month.
  eg.

  // To get the total number of days in February.
  let _givenFullYear = 2016;
  let _givenMonth = 1;
  let _totalNumberOfDays = new Date(_givenFullYear, _givenMonth + 1, 0).getDate();
  console.log(_totalNumberOfDays); // 29