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'

lib/EpdFont/EpdFontData.h

@@ -31,4 +31,5 @@ typedef struct {
   uint8_t advanceY;                     ///< Newline distance (y axis)
   int ascender;                         ///< Maximal height of a glyph above the base line
   int descender;                        ///< Maximal height of a glyph below the base line
+  bool is2Bit;
 } EpdFontData;