Allow disabling anti-aliasing via a setting (#241)

## Summary

Fixes https://github.com/daveallie/crosspoint-reader/issues/233

## Additional Context

By disabling the Text Anti-Aliasing in the settings, you can get faster
black-and-white page turns that work exactly like the stock firmware,
instead of having an additional flash after rendering (see issue linked
above for example).

Tested on the X4 and confirmed working.

---------

Co-authored-by: Dave Allie <dave@daveallie.com>

src/CrossPointSettings.h

@@ -60,6 +60,7 @@ class CrossPointSettings {
   uint8_t statusBar = FULL;
   // Text rendering settings
   uint8_t extraParagraphSpacing = 1;
+  uint8_t textAntiAliasing = 1;
   // Duration of the power button press
   uint8_t shortPwrBtn = 0;
   // EPUB reading orientation settings