ansi-term and line mode

[Chong Yidong]

I noticed that ansi-term starts out in char-mode, in which keystrokes
are passed directly to the shell.  That's fine, but it can be a bit
confusing to the new user, especially since commands like C-x C-c stop
working.

I recommend adding an echo area message when ansi-term starts up, saying
something like:

 "Starting ansi-term in char mode.  Type C-c C-j to switch to line mode."

The functions term-line-mode and term-char-mode should also issue
similar messages.

Could you implement this?

Thanks.