Added better comments to CREATE_KEYMAP() & LayerCount declarations

Also improved comment in Layer.on() conditional

src/layers.cpp

@@ -8,7 +8,9 @@ Key Layer_::liveCompositeKeymap[ROWS][COLS];
 uint8_t Layer_::activeLayers[ROWS][COLS];
 Key(*Layer_::getKey)(uint8_t layer, byte row, byte col) = Layer.getKeyFromPROGMEM;
 
-// The total number of defined layers in the firmware sketch keymaps[] array
+// The total number of defined layers in the firmware sketch keymaps[]
+// array. If the keymap wasn't defined using CREATE_KEYMAP() in the
+// sketch file, LayerCount gets the default value of zero.
 uint8_t LayerCount __attribute__((weak)) = 0;
 
 static void handleKeymapKeyswitchEvent(Key keymapEntry, uint8_t keyState) {
@@ -128,7 +130,8 @@ void Layer_::move(uint8_t layer) {
 }
 
 void Layer_::on(uint8_t layer) {
-  // If we're trying to turn on a layer that doesn't exist; abort
+  // If we're trying to turn on a layer that doesn't exist, abort (but
+  // if the keymap wasn't defined using CREATE_KEYMAP(), proceed anyway
   if (LayerCount != 0 && layer >= LayerCount)
     return;
 

src/layers.h

@@ -4,6 +4,9 @@
 #include "key_defs.h"
 #include KALEIDOSCOPE_HARDWARE_H
 
+// Macro for defining the keymap. This should be used in the sketch
+// file (*.ino) to define the keymap[] array that holds the user's
+// layers. It also computes the number of layers in that keymap.
 #define CREATE_KEYMAP(layers...)				\
   const Key keymaps[][ROWS][COLS] PROGMEM = { layers };		\
   uint8_t LayerCount = sizeof(keymaps) / sizeof(*keymaps);