LCD core move buf ptr and address look up function viewport struct

I'm currently running up against the limitations of the lcd_draw functions
I want these functions to be able to be used on any size buffer not
just buffers with a stride matching the underlying device

[DONE] allow the framebuffer to be decoupled from the device framebuffer
[DONE need examples] allow for some simple blit like transformations
[DONE] remove the device framebuffer from the plugin api
[DONE}ditto remote framebuffer
[DONE] remove _viewport_get_framebuffer you can call struct *vp = lcd_set_viewport(NULL) and vp->buffer->fb_ptr

while remote lcds may compile (and work in the sim) its not been tested on targets

[FIXED] backdrops need work to be screen agnostic

[FIXED] screen statusbar is not being combined into the main viewport correctly yet

[FIXED] screen elements are displayed incorrectly  after switch to void*

[FIXED] core didn't restore proper viewport on splash etc.

[NEEDS TESTING] remote lcd garbled data

[FIXED] osd lib garbled screen on bmp_part

[FIXED] grey_set_vp needs to return old viewport like lcd_set_viewport

[FIXED] Viewport update now handles viewports with differing buffers/strides by copying to the main buffer

[FIXED] splash on top of WPS leaves old framebuffer data (doesn't redraw)
[UPDATE] refined this a bit more to have clear_viewport set the clean bit and have skin_render do its own screen clear
scrolling viewports no longer trigger wps refresh
also fixed a bug where guisyncyesno was displaying and then disappearing

[ADDED!] New LCD macros that allow you to create properly size frame buffers in you desired size without wasting bytes
(LCD_ and LCD_REMOTE_)
LCD_STRIDE(w, h) same as STRIDE_MAIN
LCD_FBSTRIDE(w, h) returns target specific stride for a buffer W x H
LCD_NBELEMS(w, h) returns the number of fb_data sized elemenst needed for a buffer W x H
LCD_NATIVE_STRIDE(s) conversion between rockbox native vertical and lcd native stride (2bitH)
test_viewports.c has an example of usage

[FIXED!!] 2bit targets don't respect non-native strides
[FIXED] Few define snags

Change-Id: I0d04c3834e464eca84a5a715743a297a0cefd0af

apps/screen_access.c

@@ -35,6 +35,7 @@
 #include "backlight.h"
 #include "screen_access.h"
 #include "backdrop.h"
+#include "viewport.h"
 
 /* some helper functions to calculate metrics on the fly */
 static int screen_helper_getcharwidth(void)
@@ -87,7 +88,17 @@ static void screen_helper_put_line(int x, int y, struct line_desc *line,
     va_end(ap);
 }
 
+void screen_helper_lcd_viewport_set_buffer(struct viewport *vp, struct frame_buffer_t *buffer)
+{
+    viewport_set_buffer(vp, buffer, SCREEN_MAIN);
+}
+
 #if NB_SCREENS == 2
+void screen_helper_lcd_remote_viewport_set_buffer(struct viewport *vp, struct frame_buffer_t *buffer)
+{
+    viewport_set_buffer(vp, buffer, SCREEN_REMOTE);
+}
+
 static int screen_helper_remote_getcharwidth(void)
 {
     return font_get(lcd_remote_getfont())->maxwidth;
@@ -156,7 +167,11 @@ struct screen screens[NB_SCREENS] =
         .has_disk_led=true,
 #endif
         .set_drawmode=&screen_helper_set_drawmode,
+        .init_viewport=&lcd_init_viewport,
         .set_viewport=&lcd_set_viewport,
+        .set_viewport_ex=&lcd_set_viewport_ex,
+        .viewport_set_buffer = &screen_helper_lcd_viewport_set_buffer,
+        .current_viewport = &lcd_current_viewport,
         .getwidth=&lcd_getwidth,
         .getheight=&lcd_getheight,
         .getstringsize=&lcd_getstringsize,
@@ -221,7 +236,6 @@ struct screen screens[NB_SCREENS] =
         .backdrop_load=&backdrop_load,
         .backdrop_show=&backdrop_show,
 #endif
-        .set_framebuffer = (void*)lcd_set_framebuffer,
 #if defined(HAVE_LCD_COLOR)    
         .gradient_fillrect = lcd_gradient_fillrect,
         .gradient_fillrect_part = lcd_gradient_fillrect_part,
@@ -241,7 +255,11 @@ struct screen screens[NB_SCREENS] =
         .getcharheight=screen_helper_remote_getcharheight,
         .has_disk_led=false,
         .set_drawmode=&lcd_remote_set_drawmode,
+        .init_viewport=&lcd_remote_init_viewport,
         .set_viewport=&lcd_remote_set_viewport,
+        .set_viewport_ex=&lcd_remote_set_viewport_ex,
+        .viewport_set_buffer = &screen_helper_lcd_remote_viewport_set_buffer,
+        .current_viewport = &lcd_remote_current_viewport,
         .getwidth=&lcd_remote_getwidth,
         .getheight=&lcd_remote_getheight,
         .getstringsize=&lcd_remote_getstringsize,
@@ -307,7 +325,6 @@ struct screen screens[NB_SCREENS] =
         .backdrop_load=&remote_backdrop_load,
         .backdrop_show=&remote_backdrop_show,
 #endif
-        .set_framebuffer = (void*)lcd_remote_set_framebuffer,
         .put_line = screen_helper_remote_put_line,
     }
 #endif /* NB_SCREENS == 2 */