* allout.el (allout-yank-processing): Fix injection of extra space between

bullet and non-whitespace character in first topic when pasting, ensuring
that the actual spacing in the pasted topic following the bullet char is
preserved.  This extra space was causing pasted encrypted topics to get a
decrypted status even when the content was actually still encrypted.  Now
the decryption status from before the paste is preserved.

(allout-flag-region): Set all allout overlays so they evaporate when
reduced to zero length (evanescent), to prevent overlay leakage.

lisp/allout.el

@@ -4605,8 +4605,7 @@ however, are left exactly like normal, non-allout-specific yanks."
                                         ; and delete residual subj
                                         ; prefix digits and space:
                      (while (looking-at "[0-9]") (delete-char 1))
-                     (if (looking-at " ")
-                         (delete-char 1))))
+                     (delete-char -1)))
                   ;; Assert new topic's bullet - minimal effort if unchanged:
                   (allout-rebullet-heading (string-to-char prefix-bullet)))
               (exchange-point-and-mark))))
@@ -4736,6 +4735,7 @@ arguments as this function, after the exposure changes are made."
   (when flag
     (let ((o (make-overlay from to nil 'front-advance)))
       (overlay-put o 'category 'allout-exposure-category)
+      (overlay-put o 'evaporate t)
       (when (featurep 'xemacs)
         (let ((props (symbol-plist 'allout-exposure-category)))
           (while props