Got rid of (most of) all of the warnings.

src/effect_big_clock.cpp

@@ -11,7 +11,7 @@ void BigClockEffect::drawNumber(uint8_t number, int x, int y, CRGB color) {
 }
 
 void BigClockEffect::drawText(char *text, int x, int y, CRGB color) {
-  for (int i = 0; i < strlen(text); i++) {
+  for (uint8_t i = 0; i < strlen(text); i++) {
     drawSprite(font_char(numbers4x7, text[i]), x + i * 4, y, color);
   }
 }