Unicode WinCompose input method

quantum/process_keycode/process_unicode.c

@@ -42,6 +42,11 @@ void unicode_input_start (void) {
     register_code(KC_PPLS);
     unregister_code(KC_PPLS);
     break;
+  case UC_WINC:
+    register_code(KC_RALT);
+    unregister_code(KC_RALT);
+    register_code(KC_U);
+    unregister_code(KC_U);
   }
   wait_ms(UNICODE_TYPE_DELAY);
 }

quantum/process_keycode/process_unicode.h

@@ -3,10 +3,11 @@
 
 #include "quantum.h"
 
-#define UC_OSX 0
-#define UC_LNX 1
-#define UC_WIN 2
-#define UC_BSD 3
+#define UC_OSX 0  // Mac OS X
+#define UC_LNX 1  // Linux
+#define UC_WIN 2  // Windows 'HexNumpad'
+#define UC_BSD 3  // BSD (not implemented)
+#define UC_WINC 4 // WinCompose https://github.com/samhocevar/wincompose
 
 #ifndef UNICODE_TYPE_DELAY
 #define UNICODE_TYPE_DELAY 10