Energy efficient restructuring

[blahsd]

In order to make the widget more energy-efficient, it will have to be restructured so that only functions with similar required refresh times are grouped together – that way it will be possible to keep refreshes to a minimum. This is a tentative structure, sorted by frequency at which the widget must refresh in order to be funcitonal:

• Never: app-launcher, bar-top, bar-botton
• Few times a day: date, weather
• Every few minutes: system-monitor, battery
• Constantly: music-player, volume, time, desktops, window/task-manager

[blahsd]

This is now under development on branch greendev