Allow regex capture tokens in command line for alias

[Brickcaster]

Brief summary of issue / Description of requested feature:

Capture text in pattern via (.*) or whatever desired pattern.
Regurgitate it in command via $1 or whichever captured group it was.

Steps to reproduce the issue / Reasons for adding feature:

1. This simplifies many aliases to be regex-only, instead of regex + lua.

[vadi2]

What about using send("mycommand f{matches[2]}") in Lua, would that work?

Reason I say is while this would be good for experienced MUD veterans from other clients, but for anyone coming in new to Mudlet (what we're actually aiming at) it'll be confusing between the Command which can do some sort of (but not really) logic and the actual Lua code box. Right now the line between them is pretty clear, either you have as-is text or Lua for anything more.

[demonnic]

just a note, it would be send(f"mycommand {matches[2]}") or send(f("mycommand {matches[2]}"))

[Brickcaster]

Regex capture tokens are a relatively common feature of regex implementations. It would be more natural for anyone with experience with regex to follow this behavior.

Additionally, this is intended to be an alternative workflow, not a replacement to existing methods. Both regex only and regex + lua methods could be supported

[vadi2]

That's a fair way to look at it 👍