Minor update

I've just updated the game with some minor fixes.  No content update yet, sorry.

I've made an auto-solver for the levels to determine the best possible scores.  In some cases I found out that the store needed to get a star wasn't the best possible score according to the auto-solver, so I've adjusted those.  You may see some stars disappear.

By user request, the camera now "sticks" when moving it with the mouse.  As a consequence, if you move the camera, the controls will automatically change so that the movement is still relative to your point of view (ie. "right" will move the cube to whichever direction looks is closer to "right" on the screen).

By user request, it is now possible to toggle sounds (as well as music, which was already possible).

It is now possible to use the left thumbstick on a gamepad to control the menus and the game itself.  However, the level select screen does not work with gamepad yet.

A workaround has been added for a buggy Intel driver on Windows.  Furthermore, I've updated from Panda3D 1.0.2 to 1.0.4.1, which may address additional bugs.