[Calendar] Add option disabledDates similar to disabledDaysOfWeek in #199

[lubber-de]

Feature Request

Description

Add an option disabledDates to the calendar. This should hold an array of Date Objects. If the calendar view contains any of the dates the appropriate cell is disabled.
This is very similar to #199

In addition, if an Array Element is an object or Array Element itself, it can also contain additional Information, why that specific date is disabled and can show this as a popup when hovering over the cell

Example

disabledDates: [{
    date: new Date(2018,9,24),
    title: 'Company Vacation',
    message: 'Office is closed, please book later'
},{
    date: new Date(2018,11,31),
    message: 'Happy new year!'
},
new Date(2019,4,11),
new Date(2021,10,3)
]

Mockup