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/gth2.h b/include/configs/gth2.h
index b1b4842..677baea 100644
--- a/include/configs/gth2.h
+++ b/include/configs/gth2.h
@@ -90,18 +90,18 @@
 #define CONFIG_CMD_IDE
 #define CONFIG_CMD_DHCP
 
-#undef CONFIG_CMD_SAVEENV
+#undef CONFIG_CMD_BDI
+#undef CONFIG_CMD_BEDBUG
+#undef CONFIG_CMD_ELF
 #undef CONFIG_CMD_FAT
 #undef CONFIG_CMD_FLASH
 #undef CONFIG_CMD_FPGA
-#undef CONFIG_CMD_MII
-#undef CONFIG_CMD_LOADS
 #undef CONFIG_CMD_LOADB
-#undef CONFIG_CMD_ELF
-#undef CONFIG_CMD_BDI
-#undef CONFIG_CMD_BEDBUG
+#undef CONFIG_CMD_LOADS
+#undef CONFIG_CMD_MII
 #undef CONFIG_CMD_NFS
-#undef CONFIG_CMD_AUTOSCRIPT
+#undef CONFIG_CMD_SAVEENV
+#undef CONFIG_CMD_SOURCE
 
 
 /*