[bug#42689] [PATCH] gnu: Add sbcl-livesupport

[Leo Famulari]

> From 1aeb04ad466937b50acd1a2540e50f59446b6d8c Mon Sep 17 00:00:00 2001
> From: Adam Kandur <rndd@tuta.io>
> Date: Wed, 12 Aug 2020 09:52:05 +0300
> Subject: [PATCH] gnu: Add sbcl-livesupport.
> 
> * gnu/packages/lisp-xyz.scm (sbcl-livesupport): New variable.

Thanks! I added the other new variables to the commit message...

> +      (description "A macro commonly used in livecoding to enable continuing 
> when errors are raised. 
> +Simply wrap around a chunk of code and it provides a restart called 
> 'continue' which ignores the error and carrys on from the end of the body.")

And fixed some issues reported by `guix lint` in the description.

Pushed as ca7eada91819c7cd5a78e144d285cd972a478a0c