Some argument not yet documented.
+Examples
+--------
+gitk v2.6.12.. include/scsi drivers/scsi::
+
+ Show as the changes since version 'v2.6.12' that changed any
+ file in the include/scsi or drivers/scsi subdirectories
+
+gitk --since="2 weeks ago" -- gitk::
+
+ Show the changes during the last two weeks to the file 'gitk'.
+ The "--" is necessary to avoid confusion with the *branch* named
+ 'gitk'
+
Author
------
Written by Paul Mackerras <paulus@samba.org>