Update Tramp version (don't merge with master)

* doc/misc/trampver.texi:
* lisp/net/trampver.el: Change version to "2.5.2.28.1".

doc/misc/trampver.texi

@@ -8,7 +8,7 @@
 @c In the Tramp GIT, the version numbers are auto-frobbed from
 @c tramp.el, and the bug report address is auto-frobbed from
 @c configure.ac.
-@set trampver 2.5.2-pre
+@set trampver 2.5.2.28.1
 @set trampurl https://www.gnu.org/software/tramp/
 @set tramp-bug-report-address tramp-devel@@gnu.org
 @set emacsver 25.1

lisp/net/trampver.el

@@ -7,7 +7,7 @@
 ;; Maintainer: Michael Albinus <michael.albinus@gmx.de>
 ;; Keywords: comm, processes
 ;; Package: tramp
-;; Version: 2.5.2-pre
+;; Version: 2.5.2.28.1
 ;; Package-Requires: ((emacs "25.1"))
 ;; Package-Type: multi
 ;; URL: https://www.gnu.org/software/tramp/
@@ -40,7 +40,7 @@
 ;; ./configure" to change them.
 
 ;;;###tramp-autoload
-(defconst tramp-version "2.5.2-pre"
+(defconst tramp-version "2.5.2.28.1"
   "This version of Tramp.")
 
 ;;;###tramp-autoload
@@ -76,7 +76,7 @@
 ;; Check for Emacs version.
 (let ((x   (if (not (string-lessp emacs-version "25.1"))
       "ok"
-    (format "Tramp 2.5.2-pre is not fit for %s"
+    (format "Tramp 2.5.2.28.1 is not fit for %s"
             (replace-regexp-in-string "\n" "" (emacs-version))))))
   (unless (string-equal "ok" x) (error "%s" x)))