Make aliases dynamic

[danyisill]

Expected:

[18:34] Install OpenBSD: based.
[18:34] ms skinee's boy toy: .alias mockb mock !!^
[18:34] BOT Simp'O'Matic: Alias added:
.mockb now maps to .mock !!^.
[18:34] ms skinee's boy toy: .mockb
[18:34] BOT Simp'O'Matic: .mOcKb NoW mApS tO .mOcK !!^.

Got:

[18:34] Install OpenBSD: based.
[18:34] ms skinee's boy toy: .alias mockb mock !!^
[18:34] BOT Simp'O'Matic: Alias added:
.mockb now maps to .mock based.

[Demonstrandum]

!! is part of the command preprocessing, and just text-replaces right before the command is execute, just like in POSIX shells.

It is still useful to have it not be dynamic, so I think I'll add a dynamic version, say $!! along with $reply. Of course, the dynamic expansions will only be meaningful to use in the context of aliases and functions (when we eventually get around to adding that). Otherwise, $!! should act exactly like !!.

The way it should be implemented is that first, we identify that it is a command, if so, we expand history (excluding $...). Then we do alias expansion. Once that's done, the final stage is to expand the dynamic variables, i.e. $1, $2, $reply, $!!, etc.

Anyone feel like assigning themselves this issue?