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>
diff --git a/include/configs/omap3_pandora.h b/include/configs/omap3_pandora.h
index fb4e50d..40107a6 100644
--- a/include/configs/omap3_pandora.h
+++ b/include/configs/omap3_pandora.h
@@ -163,7 +163,7 @@
 		"rootfstype=jffs2\0" \
 	"loadbootscript=fatload mmc 0 ${loadaddr} boot.scr\0" \
 	"bootscript=echo Running bootscript from mmc ...; " \
-		"autoscr ${loadaddr}\0" \
+		"source ${loadaddr}\0" \
 	"loaduimage=fatload mmc 0 ${loadaddr} uImage\0" \
 	"mmcboot=echo Booting from mmc ...; " \
 		"run mmcargs; " \