Feature: retrieve files from trash

[takluyver]

In a GUI application considering using send2trash, we would like to have an 'undo' button, similar to the experience when you delete a conversation in GMail. I've no idea how hard this would be to implement, but it would be nice if S2T provided a simple API to get a file back. Something like:

trash_handle = send2trash('some_file')
restore(trash_handle)

Cross link jupyter/notebook#165