More hacks to evil-paredit

- Make rectangle delete work.  Currently this uses the simple heuristic
  to just allow any edit to regions not containing the paren chars.
- Make evil-paredit-delete do the right thing when deleting in region:

If | | marks the beg and end of region then hidding 'd' in this case:

(defun foo ()
| (bar)
  (baz)) |

results in:

(defun foo ()
  )