Package fix/takeover: AC-Vector

[Jan Rochel]

> Here's my attempt to take over an apparently unmaintained package:
> https://hackage.haskell.org/package/AC-Vector

Here's the code repository I have created for the package:
https://github.com/jrochel/AC-Vector

I'd like to get this package back to work as I have some older packages
myself which depend on it, such as:
https://hackage.haskell.org/package/graph-rewriting-layout

The maintainer hasn't responded in four months.

Thanks in advance,
Jan