DS Classic Menu: Improve clock hands and add outer shadow to the clock & calendar

[mentusfentus]

What's changed?

• Improved clock needles/hands: The clock's line renderer now uses the Bresenham's line algorithm, which has less irregularities when pointing diagonally and is much faster than the previous one.
• Added the outer shadow to the clock and calendar. The result is not 1:1 to the original menu, but in my opinion this looks much nicer than before. This is done using semi-transparent textures, so it works well with custom themes that replaces the background

Where have you tested it?

Nintendo DSi XL with Unlaunch
melonDS 0.9.5

---

Pull Request status

• This PR has been tested using the latest version of devkitARM and libnds.