Add "source" command; prepare removal of "autoscr" command

According to the doc/feature-removal-schedule.txt, the "autoscr"
command will be replaced by the "source" command in approximately 6
months from now.

This patch prepares this change and starts a 6 month transition
period as follows:

- The new "source" command has been added, which implements exactly
  the same functionlaity as the old "autoscr" command before
- The old "autoscr" command name is kept as an alias for compatibility
- Command sequences, script files atc. have been adapted to use the
  new "source" command
- Related environment variables ("autoscript", "autoscript_uname")
  have *not* been adapted yet; these will be renamed resp. removed in
  a separate patch when the support for the "autoscr" command get's
  finally dropped.

Signed-off-by: Wolfgang Denk <wd@denx.de>

doc/feature-removal-schedule.txt

@@ -8,12 +8,20 @@ file.
 ---------------------------
 
 What:	"autoscr" command
-When:	August 2009
-Why:	"autosrc" is an ugly and completely non-standard name.  The "autoscr"
-	command is deprecated and will be replaced the "source" command as
-	used by other shells such as bash.  Both commands will be supported
-	for a transition period of 6 months after which "autoscr" will be
-	removed.
+When:	Release 2009-09
+
+Why:	"autosrc" is an ugly and completely non-standard name.
+        The "autoscr" command is deprecated and will be replaced by
+
+        the "source" command as used by other shells such as bash.
+
+        Starting with March 2009, both commands will be supported for
+        a transition period of 6 months after which "autoscr" will be
+        removed. During the transition period existing scripts and
+        environment variable names remain untouched for maximum
+        compatibiltiy; thse will be changed when support for the
+        "autoscr" command get's finally dropped.
+
 Who:	Peter Tyser <ptyser@xes-inc.com>
 
 ---------------------------