implemented first version of DeletedDrone

implemented DeletedDrone. DeletedDrone was first meant to respond to
strings of more than one deleted comment, but I discovered that reddit
doesn't allow comments on deleted comments, unfortunately. Because of
this, it now responds to the first non-deleted comment immediately after
one or more deleted comments.
check to make sure target comment isn't deleted

make sure that the comment we're currently looking at isn't deleted.
that is, we want to comment on a non deleted comment which itself is on
a deleted comment.