add -i, send-email, svn, p4, etc: use "git var GIT_EDITOR"

Use the new "git var GIT_EDITOR" feature to decide what editor to
use, instead of duplicating its logic elsewhere.  This should make
the behavior of commands in edge cases (e.g., editor names with
spaces) a little more consistent.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/Documentation/config.txt b/Documentation/config.txt
index d1e2120..5181b77 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -387,9 +387,7 @@
 	Commands such as `commit` and `tag` that lets you edit
 	messages by launching an editor uses the value of this
 	variable when it is set, and the environment variable
-	`GIT_EDITOR` is not set.  The order of preference is
-	`GIT_EDITOR` environment, `core.editor`, `VISUAL` and
-	`EDITOR` environment variables and then finally `vi`.
+	`GIT_EDITOR` is not set.  See linkgit:git-var[1].
 
 core.pager::
 	The command that git will use to paginate output.  Can
diff --git a/Documentation/git-commit.txt b/Documentation/git-commit.txt
index 0578a40..3ea80c8 100644
--- a/Documentation/git-commit.txt
+++ b/Documentation/git-commit.txt
@@ -323,7 +323,7 @@
 The editor used to edit the commit log message will be chosen from the
 GIT_EDITOR environment variable, the core.editor configuration variable, the
 VISUAL environment variable, or the EDITOR environment variable (in that
-order).
+order).  See linkgit:git-var[1] for details.
 
 HOOKS
 -----
diff --git a/Documentation/git-send-email.txt b/Documentation/git-send-email.txt
index 767cf4d..c85d7f4 100644
--- a/Documentation/git-send-email.txt
+++ b/Documentation/git-send-email.txt
@@ -60,8 +60,8 @@
 The --cc option must be repeated for each user you want on the cc list.
 
 --compose::
-	Use $GIT_EDITOR, core.editor, $VISUAL, or $EDITOR to edit an
-	introductory message for the patch series.
+	Invoke a text editor (see GIT_EDITOR in linkgit:git-var[1])
+	to edit an introductory message for the patch series.
 +
 When '--compose' is used, git send-email will use the From, Subject, and
 In-Reply-To headers specified in the message. If the body of the message