When screen dimensions are shrinked, panel will be moved at the correct location but will not be resized correctly. Also,
when screen dimensions are changed again, increasing sizes, panel would not catch that. Here, 'the hack' is to track
root window dimension changes and react on that, since relaying on _NET_WORKAREA is not always good; struts dimentions affects workarea size.
Main menu now has tooltips, which is Comment value from .desktop files. Also, since XdgMenuReader directly plays with MenuItem,
MenuItem::init_extensions() is used to reset uncommon values.
Removing usage of EDE_PANEL_APPLET_CLASS since there is no much usage of it. Also, marked all applet widgets as EDE_PANEL_WIDGET_TYPE so panel knows it is widget.
Added license info in some code, but whole ede2 tree needs to be revised for that.
This change should make base applet code easier to modify without modifying applets itself. This is also
a starting point for implementation of better routing netwm messages to applets without adding specific listener
to each applet.
