Insteon: Add Sync_All_Links Routine for Multigroup items; Add MultigroupDevice Package

Added a package called MutigroupDevice in BaseInsteon.pm.  The purpose of this package is to contain routines specific to all multigroup devices.

Added Sync_All_links routines to MultigroupDevice.  The routine will sync all links between any group on the device.  Useful for KeyPadLincs and RemoteLincs and such.

Fixes #85