mysql-native v3.0.0: Update from `vibe-d:core` to `vibe-core`

[Nick Sabalausky (Abscissa)]

The mysql-native package is a native all-D client library for MySQL and 
MariaDB. If vibe-d is included in your project, it will use vibe-d 
networking, otherwise it will use Phobos networking.

https://github.com/mysql-d/mysql-native

In this update, mysql-native's vibe-d support has switched from the old 
`vibe-d:core` package to the new `vibe-core` package. Several other 
improvements are included as well. See the changelog for details: < 
https://github.com/mysql-d/mysql-native/blob/master/CHANGELOG.md >. Big 
thanks to @SingingBush and @schveiguy for their contributions in this 
release.

On the near horizon, work on v3.1.0 and v4.0.0 is already well underway 
which will make much of mysql-native @safe. This is necessitating a 
change away from using Phobos's Variant for data, but we think this will 
be well worth it as the new replacement offers a much nicer API. And of 
course, effort is being made to make migrating go as smoothly and simply 
as possible.