kotlin extension & modify ignore file

[Stanllley]

when use kotlin , we can do like this

example:
val calendarView = findCalendarView(this,R.id.calendarView){

        //do something...
        maxMultiSelectSize = 1
        setSelectSingleMode()
        setOnMonthChangeListener { year, month ->
            Toast.makeText(this@KotlinTestActivity, "$year : $month",Toast.LENGTH_SHORT).show()
        }
        ......

}
val singleSelectMode = calendarView.isSingleSelectMode