wmtweaks and xfwm settings plugins

[Jani Monoses]

> 
> Because the wmtweaks plugin covers advanced features that are not meant
> for regular users. A bit like the tweakui utility for Windows.

The difference in advancedness is not that much between various features 
presented in the two plugins. IMHO it would be better not to confuse the 
user who starts up the settings dialog and has two wm related plugins to 
chose from. The existing tweaks would be better as a new tab in the wm 
plugin with some options moved over to other tabs (there's already a 
Focus tab setting put the two tweaks there, same with the workspace one)
Raise when any button is clicked from tweaks might be near raise on 
click in the wm plugin.
Even better would be tabs named windows and workspaces just like focus 
is and put the contents of wmtweaks in these three categories.

This way people won't forget in which of the two wm plugins their option 
is and there would be less plugins to load ;)

Jani