Fixed bugs and updated the samples:
1. Replaced the VSync interrupt number (2) with the appropriate definition from kernel.h: kINTC_VBLANK_START.
2. Added missing header includes to samples, reordered the includes to include the basic header files first, standardized the main() function definitions to main(int argc, char *argv[]) so that beginners can learn the right way of defining the main function.
3. Declared local functions as static.
4. Changed all instances of "sync.l; ei" at the end of interrupt handlers to the macro that does the same thing: ExitHandler().
5. Removed jbit's workaround within gsKit_prim_sprite_texture_3d, which was supposed to provide "pixel-perfect" texture drawing. I removed it because it causes textures to be visibly scaled when nearest filtering is used, plus it is possible to implement the hack from the outside of the function.