OLED screen optimizations for lower power use

Please consider a low-power OLED mode with the maps where the Gaia UI and screen are predominantly black, with routes, contours, etc. in color.  This wouldn’t work with scanned maps, but should be possible with vector maps. 

And a "dark-mode" so other non-map pages are OLED-friendly. (Black background, colored text, colored small images ok, too...or use the dark mode images if they can be implemented (such as track thumbnail images)