Merge branch 'maint-1.7.8' into maint

By Thomas Rast
* maint-1.7.8:
  Document the --histogram diff option

Documentation/diff-options.txt

@@ -52,6 +52,9 @@ endif::git-format-patch[]
 --patience::
 	Generate a diff using the "patience diff" algorithm.
 
+--histogram::
+	Generate a diff using the "histogram diff" algorithm.
+
 --stat[=<width>[,<name-width>[,<count>]]]::
 	Generate a diffstat.  You can override the default
 	output width for 80-column terminal by `--stat=<width>`.