Changing the 'Howdy, user' on the toolbar for WordPress

I haven’t been doing much on here in the way of computing lately, so to get back to it, here’s a WordPress plugin I wrote to get a better idea of how the plugin settings API works.

It’s very basic, all it does is change the ‘Howdy’ text in the toolbar (front and backend) to whatever you want by altering the toolbar by injecting the new greeting.

It was good fun to write, so here it is!