Use row and column remapping to change either row or column addressing
for each orientation. This removes the need to reverse the drawing
direction of either x or y in the drawing routines. However in the 90
and 270 case x and y must still be swapped.
Also, rename the SSD1306 remapping command names so they are more
descriptive.
You can now have a main color display and a secondary monochrome display.
You can now optionally set GDISP_PIXELFORMAT to any color or grayscale format for your application and the driver will internally convert to the display hardware format.