Horizontal Mouse Scrolling Support in Kaleidoscope-Mousekeys

using the new moveMouse function in kaleidoscope::hid we can have
horizontal mouse scrolling.

README.md

@@ -77,6 +77,8 @@ properties (see below).
 
 * `Key_mouseScrollUp`, `Key_mouseScrollDn`: Scroll the mouse wheel up or down,
   respectively.
+* `Key_mouseScrollL`, `Key_mouseScrollR`: Scroll the mouse wheel left or right,
+  respectively.
   
 ### Buttons
 

src/Kaleidoscope-MouseKeys.cpp

@@ -29,6 +29,10 @@ void MouseKeys_::scrollWheel(uint8_t keyCode) {
     kaleidoscope::hid::moveMouse(0, 0, wheelSpeed);
   else if (keyCode & KEY_MOUSE_DOWN)
     kaleidoscope::hid::moveMouse(0, 0, -wheelSpeed);
+  else if (keyCode & KEY_MOUSE_LEFT)
+    kaleidoscope::hid::moveMouse(0, 0, 0, -wheelSpeed);
+  else if (keyCode & KEY_MOUSE_RIGHT)
+    kaleidoscope::hid::moveMouse(0, 0, 0, wheelSpeed);
 }
 
 void MouseKeys_::loopHook(bool postClear) {

src/MouseKeyDefs.h

@@ -36,8 +36,8 @@
 #define Key_mouseDnR      (Key) { KEY_MOUSE_DOWN | KEY_MOUSE_RIGHT, KEY_FLAGS|SYNTHETIC|IS_MOUSE_KEY }
 #define Key_mouseScrollUp (Key) { KEY_MOUSE_WHEEL | KEY_MOUSE_UP, KEY_FLAGS|SYNTHETIC|IS_MOUSE_KEY }
 #define Key_mouseScrollDn (Key) { KEY_MOUSE_WHEEL | KEY_MOUSE_DOWN, KEY_FLAGS|SYNTHETIC|IS_MOUSE_KEY }
-#define Key_mouseScrollL
+#define Key_mouseScrollL  (Key) { KEY_MOUSE_WHEEL | KEY_MOUSE_LEFT, KEY_FLAGS|SYNTHETIC|IS_MOUSE_KEY }
-#define Key_mouseScrollR
+#define Key_mouseScrollR  (Key) { KEY_MOUSE_WHEEL | KEY_MOUSE_RIGHT, KEY_FLAGS|SYNTHETIC|IS_MOUSE_KEY }
 #define Key_mouseBtnL     (Key) { KEY_MOUSE_BUTTON | KEY_MOUSE_BTN_L, KEY_FLAGS | SYNTHETIC | IS_MOUSE_KEY }
 #define Key_mouseBtnM     (Key) { KEY_MOUSE_BUTTON | KEY_MOUSE_BTN_M, KEY_FLAGS | SYNTHETIC | IS_MOUSE_KEY }
 #define Key_mouseBtnR     (Key) { KEY_MOUSE_BUTTON | KEY_MOUSE_BTN_R, KEY_FLAGS | SYNTHETIC | IS_MOUSE_KEY }