Moving all class declarations to EDE_PANEL_APPLET_CLASS macro.

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.

ede-panel/applets/demo/AppletDemo.cpp

@@ -4,7 +4,7 @@
 #include <FL/Fl.H>
 #include <stdio.h>
 
-class MyButton : public Fl_Button {
+EDE_PANEL_APPLET_CLASS(MyButton, Fl_Button) {
 public:
 	MyButton() : Fl_Button(0, 0, 90, 25, "xxx") { 
 		color(FL_RED);