This is not really a plugin. This is a base class implementation that can be used to create plugins.
Basic idea was to shorten the plugin development time. When you start working on a new plugin, you need to create a lot of basic code for initialization of options page, widget initialization and this is even more complicated if you want a plugin to support multi instance widgets. And this you need to repeat for every plugin.
And, repeating this every time gets very tiresome and mistakes are easily made. So, you might want to try using this base class, extending it and setting only the things you need.
The GD Plugin Core class implements following features: