Add mouse constants.

This patch adds the following globals: MOUSE_LEFT, MOUSE_RIGHT,
MOUSE_MIDDLE, MOUSE_ALL

Signed-off-by: xSlendiX <slendi@socopon.com>

Author: slendidev

lua_api.cpp

@@ -327,6 +327,12 @@ INPUT_PULLUP = 2\n\
   luaL_dostring(L, "\
 LOW = 0\n\
 HIGH = 1\n\
+\n");
+  luaL_dostring(L, "\
+MOUSE_LEFT = 1\n\
+MOUSE_RIGHT = 2\n\
+MOUSE_MIDDLE = 4\n\
+MOUSE_ALL = 7\n\
 \n");
 
   luaL_dostring(L, "function gui(char)\n\