replace framebuffer.h include with forward declaration

instead of including framebuffer.h almost everywhere, replace it with
class CFrameBuffer forward declarations and/or generic system includes.
Add a hack to define fb_pixel_t to config.h (one reason for
framebuffer.h includes was the fb_pixel_t define)

src/driver/simple_display.cpp

@@ -25,7 +25,6 @@
 #endif
 
 #include <driver/lcdd.h>
-#include <driver/framebuffer.h>
 
 #include <global.h>
 #include <neutrino.h>