start modularizing framebuffer acceleration architecture

This is just copied framebuffer.{h,cpp} => fb_generic.{h,cpp}
The idea is to implement CFrameBuffer as generic framebuffer class that
does work on almost every hardware without acceleration and / or
hardware dependencies.
CFbAccel will be a derived class (and different on many architectures)
which implements the accelerated functions.
This does not yet compile, verbatim copies to track development history.

src/driver/framebuffer.h

@@ -21,7 +21,7 @@
 	Boston, MA  02110-1301, USA.
 */
 
-#include "framebuffer_ng.h"
+#include "fb_generic.h"
 #if 0
 
 #ifndef __framebuffer__