Documentation/ToolsForGit.txt: Tools for developing Git

This document gathers tips, scripts and configuration file to help
people working on Git’s codebase use their favorite tools while
following Git’s coding style.

Move the part about Emacs configuration from CodingGuidelines to
ToolsForGit.txt because it's the purpose of the new file centralize the
information about tools.

But, add a mention to Documentation/ToolsForGit.txt in CodingGuidelines
because there is also information about the coding style in it.

Helped-by: Matthieu Moy <Matthieu.Moy@univ-lyon1.fr>
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: COGONI Guillaume <cogoni.guillaume@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/CodingGuidelines

@@ -43,7 +43,10 @@ the overall style of existing code. Modifications to existing
 code is expected to match the style the surrounding code already
 uses (even if it doesn't match the overall style of existing code).
 
-But if you must have a list of rules, here they are.
+But if you must have a list of rules, here are some language
+specific ones. Note that Documentation/ToolsForGit.txt document
+has a collection of tips to help you use some external tools
+to conform to these guidelines.
 
 For shell scripts specifically (not exhaustive):
 
@@ -492,17 +495,6 @@ For Perl programs:
 
  - Learn and use Git.pm if you need that functionality.
 
- - For Emacs, it's useful to put the following in
-   GIT_CHECKOUT/.dir-locals.el, assuming you use cperl-mode:
-
-    ;; note the first part is useful for C editing, too
-    ((nil . ((indent-tabs-mode . t)
-                  (tab-width . 8)
-                  (fill-column . 80)))
-     (cperl-mode . ((cperl-indent-level . 8)
-                    (cperl-extra-newline-before-brace . nil)
-                    (cperl-merge-trailing-else . t))))
-
 For Python scripts:
 
  - We follow PEP-8 (http://www.python.org/dev/peps/pep-0008/).