Move to SDK EInkDisplay and enable anti-aliased 2-bit text (#5)

* First pass at moving to SDK EInkDisplay library

* Add 2-bit grayscale text and anti-aliased rendering of text

* Render status bar for empty chapters

* Refresh screen every 15 pages to avoid ghosting

* Simplify boot and sleep screens

* Give FileSelectionScreen task more stack memory

* Move text around slightly on Boot and Sleep screens

* Re-use existing buffer and write to whole screen for 'partial update'

platformio.ini

@@ -34,7 +34,7 @@ build_flags =
 
 ; Libraries
 lib_deps =
-  zinggjm/GxEPD2@^1.6.5
   https://github.com/leethomason/tinyxml2.git#11.0.0
   BatteryMonitor=symlink://open-x4-sdk/libs/hardware/BatteryMonitor
   InputManager=symlink://open-x4-sdk/libs/hardware/InputManager
+  EInkDisplay=symlink://open-x4-sdk/libs/display/EInkDisplay