Set QML Uis as a default property

It is no longer requiered to manually define the "uis" array. Simply
define "Ui" components directly inside the "Plugin" component
Now properly creates a widget from a QQuickItem
Small refactoring

SystemTray members naming
Added a new build configuration
Fixed icon for plug-ins without a shortcut defined
Improved image engine performance
Added a redis configuration file

Now dumps in the appdata folder
Now supports drag and drop of local plug-ins
Exposed encoding utilities to QML

Updated plugins accordingly
Fixed a possible crash due to the dynamic image engine

The rainbow plug-in could cause a crash when active. If the user deleted
a plug-in, the action widget was still notified to change its icons
color even though it was deleted.