Widget Layouts

[gentlegiantJGC]

My vision for Amulet is to have widgets implemented by plugins that the user can position as per their requirements.
I will refer to the unique positioning of widgets as a layout.
The main window will have a list of buttons that the user can press to switch between layouts.
Plugins can implement layouts and the user can modify to their requirements and add entirely new layouts.

To support this we will need:

• a public function to register new layouts
• a public function to enable a layout
• a signal to notify of a layout change
• a public function to get a layout's state
• a public function to set a layout's state
• a config entry to store user's changes to the layouts and custom layouts
• a config entry for the order to show layout buttons in

It makes most sense to implement this within the main window plugin.