Prepare for release

[trigg]

Debates remaining:

• feature PR panel: add power profile switching to battery widget #457
• housekeeping PR panel: split default-icon from widget-icon #458

After these, we should look at only bugfix, documentation and housekeeping, in preparation for a release.

[AKArien]

Note : WCM should be updated to read the new config path at prefix/wf-shell/metadata instead of prefix/wayfire/metadata/wf-shell