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/lwmon5.h b/include/configs/lwmon5.h
index 05055c8..777a4d6 100644
--- a/include/configs/lwmon5.h
+++ b/include/configs/lwmon5.h
@@ -313,7 +313,7 @@
 		"cp.b 200000 FFF80000 80000\0"			        \
 	"upd=run load update\0"						\
 	"lwe_env=tftp 200000 /tftpboot.dev/lwmon5/env_uboot.bin;"	\
-		"autoscr 200000\0"					\
+		"source 200000\0"					\
 	""
 #define CONFIG_BOOTCOMMAND	"run flash_self"