Improve Import and Export iCAL APIs and tests

• Import and Export Ical.Net Calendar and CalendarCollections by file path, stream and as string
• Simplify API removing un-necessary parameters that can be safely ignored or are overwritten by Ical.Net on serialization
• Improve test coverage for Import-IcalCalendar and Export-IcalCalendar
• Add a ImportScript to test for published updates

0.0.1

Added Cmdlets with incomplete APIs:

  "New-Calendar"
  "New-Event",
  "Add-Event",
  "New-Alarm",
  "Add-Alarm",
  "Import-Calendar", 
  "Export-Calendar"

https://www.powershellgallery.com/packages/ImportIcal/0.0.1