Cartridge (big-endian): 1234
RAM (little-endian): 4321
Source 16-bit image: 12-34 (2 pixels)
Emulated image should be 21-43 (big => little), but the word swap made it 43-21 (pixel swapped)
Output: 4321 => 2143
- Added SDL video output.
- Send VI interrupts when the currently scanned line hits the interrupt register's.
- Added some program options related to video.