Severity: wishlist

Please find attached two patches that tweaks how M-x
(execute-extended-command) works:

1. Show obsolete commands, and give their new name as an annotation.

M-x recently got the capability to show the keybindings for commands in
an annotation (in parenthesis after the command name).  This patch makes
it show new names for obsolete aliases in the same way, instead of just
refusing to show them.  This should help users ease into the new name
less abruptly and disruptively, instead of having it just disappearing
from M-x and be nowhere to be found.

As an added bonus, we could more confidently mark an alias such as
`display-time-world' obsolete (without worrying that it will just be
gone in the next release).

(Yes, if you type out the full name, you can still call it, but chances
are that many users are very reliant on tab completion and will assume
that it's just gone if it doesn't show up.)

2. Show the function that aliases point to in the same way.