Use font ascender height for baseline offset (#139)

## Summary

* Use font ascender height for baseline offset
* Previously was using font height, but when rendering the font (even
from y = 0), there would be a lot of top margin
* Font would also go below the "bottom of the line" as we were using the
full font height as the baseline

## Additional Context

* This caused some text to move around, I've fixed everything I can
* Notably it moves the first line of font a little closer to the top of
the page

src/activities/home/HomeActivity.cpp

@@ -106,7 +106,7 @@ void HomeActivity::render() const {
   renderer.drawCenteredText(READER_FONT_ID, 10, "CrossPoint Reader", true, BOLD);
 
   // Draw selection
-  renderer.fillRect(0, 60 + selectorIndex * 30 + 2, pageWidth - 1, 30);
+  renderer.fillRect(0, 60 + selectorIndex * 30 - 2, pageWidth - 1, 30);
 
   int menuY = 60;
   int menuIndex = 0;