Add send2trash, General Config/Send to trash, and catch show dir not found exception.

Add send2trash, a small package that sends files to the Trash (or Recycle Bin) natively and on all platforms. If send2trash is found not compatible, the user can use the default delete and manually delete failed send2trash files.
Add General Config/Misc/Send to trash for actions that involve removing shows and log rotation.
Add handling for the exception raised while deleting a show and show folder no longer exists.
Merge pull request #101 from JackDandy/feature/AddSend2TrashLib

Add send2trash, General Config/Send to trash, and catch show dir not found exception.