Constify certain variables

Where possible, variables definitions were constified to catch
unintentional changes.

Signed-off-by: Max Görner <max@familie-goerner.eu>

src/Kaleidoscope-Model01-TestMode.cpp

@@ -57,10 +57,10 @@ void TestMode_::set_leds(cRGB color) {
 }
 
 void TestMode_::test_leds(void) {
-  cRGB red = CRGB(201, 0, 0);
-  cRGB blue = CRGB(0, 0, 201);
-  cRGB green = CRGB(0, 201, 0);
-  cRGB brightWhite = CRGB(160, 160, 160);
+  constexpr cRGB red = CRGB(201, 0, 0);
+  constexpr cRGB blue = CRGB(0, 0, 201);
+  constexpr cRGB green = CRGB(0, 201, 0);
+  constexpr cRGB brightWhite = CRGB(160, 160, 160);
 
   // make all the LEDs bright red
   set_leds(red);
@@ -82,14 +82,14 @@ void TestMode_::test_leds(void) {
 
 void TestMode_::handleKeyEvent(side_data_t *side, keydata_t *oldState, keydata_t *newState, uint8_t row, uint8_t col, uint8_t col_offset) {
 
-  cRGB red = CRGB(201, 0, 0);
-  cRGB blue = CRGB(0, 0, 201);
-  cRGB green = CRGB(0, 201, 0);
+  constexpr cRGB red = CRGB(201, 0, 0);
+  constexpr cRGB blue = CRGB(0, 0, 201);
+  constexpr cRGB green = CRGB(0, 201, 0);
 
-  uint8_t keynum = (row * 8) + (col);
+  const uint8_t keynum = (row * 8) + (col);
 
-  uint8_t keyState = ((bitRead(oldState->all, keynum) << 1) |
-                      (bitRead(newState->all, keynum) << 0));
+  const uint8_t keyState = ((bitRead(oldState->all, keynum) << 1) |
+                            (bitRead(newState->all, keynum) << 0));
   if (keyState == TOGGLED_ON) {
     if (side->cyclesSinceStateChange[keynum] < CHATTER_CYCLE_LIMIT) {
       bitSet(side->badKeys, keynum);