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/common/Makefile b/common/Makefile
index 23171ca..eb8e283 100644
--- a/common/Makefile
+++ b/common/Makefile
@@ -61,8 +61,8 @@
 
 # command
 COBJS-$(CONFIG_CMD_AMBAPP) += cmd_ambapp.o
-COBJS-$(CONFIG_AUTOSCRIPT) += cmd_autoscript.o
-COBJS-$(CONFIG_CMD_AUTOSCRIPT) += cmd_autoscript.o
+COBJS-$(CONFIG_SOURCE) += cmd_source.o
+COBJS-$(CONFIG_CMD_SOURCE) += cmd_source.o
 COBJS-$(CONFIG_CMD_BDI) += cmd_bdinfo.o
 COBJS-$(CONFIG_CMD_BEDBUG) += bedbug.o cmd_bedbug.o
 COBJS-$(CONFIG_CMD_BMP) += cmd_bmp.o