Tweak C-x TAB behavior changes, and update docs.

* lisp/indent.el (indent-rigidly-map): Add docstring, and move commands
into named functions.
(indent-rigidly-left, indent-rigidly-right)
(indent-rigidly-left-to-tab-stop)
(indent-rigidly-right-to-tab-stop): New functions.  Decide on
indentation direction based on bidi direction, and accumulate
sequential commands in a single undo boundary.
(indent-rigidly--pop-undo): New utility function.

* doc/emacs/indent.texi (Indentation Commands): Document C-x TAB changes.

* doc/lispref/text.texi (Region Indent): Note the new interactive
behavior of indent-rigidly.

2 files changed, 14 insertions, 11 deletions

diff --git a/doc/lispref/ChangeLog b/doc/lispref/ChangeLog
index 15730515301..ccd236403b8 100644
--- a/doc/lispref/ChangeLog
+++ b/doc/lispref/ChangeLog
@@ -1,3 +1,8 @@
+2013-12-21  Chong Yidong  <cyd@gnu.org>
+
+	* text.texi (Region Indent): Note the new interactive behavior of
+	indent-rigidly.
+
 2013-12-20  Tassilo Horn  <tsdh@gnu.org>
 
 	* numbers.texi (numbers): Document that =, <, <=, >, >= now accept
diff --git a/doc/lispref/text.texi b/doc/lispref/text.texi
index b814d553296..1deb4a6530a 100644
--- a/doc/lispref/text.texi
+++ b/doc/lispref/text.texi
@@ -2344,21 +2344,19 @@ a different meaning and does not use this variable.
 @end defvar
 
 @deffn Command indent-rigidly start end count
-This command indents all lines starting between @var{start}
+This function indents all lines starting between @var{start}
 (inclusive) and @var{end} (exclusive) sideways by @var{count} columns.
 This ``preserves the shape'' of the affected region, moving it as a
-rigid unit.  Consequently, this command is useful not only for indenting
-regions of unindented text, but also for indenting regions of formatted
-code.
+rigid unit.
 
-For example, if @var{count} is 3, this command adds 3 columns of
-indentation to each of the lines beginning in the region specified.
+This is useful not only for indenting regions of unindented text, but
+also for indenting regions of formatted code.  For example, if
+@var{count} is 3, this command adds 3 columns of indentation to every
+line that begins in the specified region.
 
-@c FIXME: I suggest using message-indent-citation as the example, or
-@c just remove this paragraph.  --xfq
-In Mail mode, @kbd{C-c C-y} (@code{mail-yank-original}) uses
-@code{indent-rigidly} to indent the text copied from the message being
-replied to.
+If called interactively with no prefix argument, this command invokes
+a transient mode for adjusting indentation rigidly.  @xref{Indentation
+Commands,,, emacs, The GNU Emacs Manual}.
 @end deffn
 
 @deffn Command indent-code-rigidly start end columns &optional nochange-regexp