Added a function to grow the number of log in the log view

The log view will show an help at its end when there is more log to
view, and the function is bound to "l" in log view.

magit.el

@@ -116,6 +116,11 @@ Setting this to nil will make it do nothing, setting it to t will arrange things
   :group 'magit
   :type 'integer)
 
+(defcustom magit-log-infinite-length 99999
+  "Number of log used to show as maximum for magit-log-cutoff-length"
+  :group 'magit
+  :type 'integer)
+
 (defcustom magit-process-popup-time -1
   "Popup the process buffer if a command takes longer than this many seconds."
   :group 'magit
@@ -1452,6 +1457,7 @@ FUNC should leave point at the end of the modified region"
     (define-key map (kbd "m") 'magit-manual-merge)
     (define-key map (kbd "M") 'magit-automatic-merge)
     (define-key map (kbd "x") 'magit-reset-head)
+    (define-key map (kbd "l") 'magit-log-show-more-entries)
     map))
 
 (defvar magit-reflog-mode-map
@@ -2133,6 +2139,23 @@ must return a string which will represent the log line.")
 	  (when message
 	    (propertize message 'face 'magit-log-message)))))
 
+(defvar magit-log-count ()
+  "internal var used to count the number of log actualy added in a buffer")
+
+(defmacro magit-create-log-buffer-sections (&rest body)
+  "Empty current buffer of text and magit's section, and then evaluate body.
+
+if the number of logs inserted in the buffer is magit-log-cutoff-length
+insert a line to tell how to insert more of them"
+  (declare (indent 0))
+  `(let ((magit-log-count 0) (inhibit-read-only t))
+     (magit-create-buffer-sections
+       ,@body
+       (if (= magit-log-count magit-log-cutoff-length)
+	   (magit-with-section "longer"  'longer
+	     (insert "type \"l\" to show more logs\n"))))))
+
+
 (defun magit-wash-log-line ()
   (beginning-of-line)
   (let ((line-re magit-log-oneline-re))
@@ -2151,6 +2174,7 @@ must return a string which will represent the log line.")
         (goto-char (point-at-bol))
         (if sha1
             (magit-with-section sha1 'commit
+              (when magit-log-count (setq magit-log-count (1+ magit-log-count)))
               (magit-set-section-info sha1)
               (forward-line))
           (forward-line))))
@@ -3306,10 +3330,27 @@ Prefix arg means justify as well."
       (let ((res (magit-git-exit-code "log" "--decorate=full" "--max-count=0")))
 	(setq magit-have-decorate (eq res 0)))))
 
+(defun magit-log-show-more-entries (&optional arg)
+  "Grow the number of log entries shown.
+
+With no prefix optional ARG, show twice as much log entries.
+With a numerical prefix ARG, add this number to the number of shown log entries.
+With a non numeric prefix ARG, show all entries"
+  (interactive "P")
+  (make-local-variable 'magit-log-cutoff-length)
+  (cond
+    ((numberp arg)
+     (setq magit-log-cutoff-length (+ magit-log-cutoff-length added)))
+    (arg
+     (setq magit-log-cutoff-length magit-log-infinite-length))
+    (t (setq magit-log-cutoff-length (* magit-log-cutoff-length 2))))
+  (magit-refresh))
+
+
 (defun magit-refresh-log-buffer (range style args)
   (magit-configure-have-graph)
   (magit-configure-have-decorate)
-  (magit-create-buffer-sections
+  (magit-create-log-buffer-sections
     (apply #'magit-git-section nil
 	   (magit-rev-range-describe range "Commits")
 	   'magit-wash-log
@@ -3366,7 +3407,7 @@ Prefix arg means justify as well."
 ;;; Reflog
 
 (defun magit-refresh-reflog-buffer (head args)
-  (magit-create-buffer-sections
+  (magit-create-log-buffer-sections
     (magit-git-section 'reflog
 		       (format "Local history of head %s" head)
 		       'magit-wash-log
@@ -3608,7 +3649,9 @@ Prefix arg means justify as well."
      (magit-show-stash info)
      (pop-to-buffer "*magit-stash*"))
     ((topic)
-     (magit-checkout info))))
+     (magit-checkout info))
+    ((longer)
+     (magit-log-show-more-entries ()))))
 
 (defun magit-show-item-or-scroll-up ()
   (interactive)

magit.texi

@@ -330,6 +330,12 @@ in one branch, but not in another, for example.
 Typing @kbd{L} (or @kbd{C-u L}) will show the log in a more verbose
 form.
 
+Magit will show only @code{magit-log-cutoff-length} entries. @kbd{l}
+will show twice as much entries. @kbd{C-u l} will show all entries,
+and given a numeric prefix argument, @kbd{l} will add this number of
+entries. You can also show more entry by typing @kbd{RET} on the text
+appended at the end of the buffer.
+
 You can move point to a commit and then cause various things to happen
 with it.  (The following commands work in any list of commit, such as
 the one shown in the @emph{Unpushed commits} section.)