Added love.mouse.hasCursor. Returns true if mouse cursors are available.

--HG--
branch : minor

src/modules/mouse/wrap_Mouse.h

@@ -34,6 +34,7 @@ int w_newCursor(lua_State *L);
 int w_getSystemCursor(lua_State *L);
 int w_setCursor(lua_State *L);
 int w_getCursor(lua_State *L);
+int w_hasCursor(lua_State *L);
 int w_getX(lua_State *L);
 int w_getY(lua_State *L);
 int w_getPosition(lua_State *L);