nes: added initial support for RP2A03 CPU.
nes: reorganized controller and CPU initialization order to manage dependencies.
nes: added initial PPU support.
nes: clock rates are now derived from a master clock.
main: added new IRQ resource type.
nes: cleaned up some resource names.
nes: RP2A03 now supports interrupts.
nes: PPU now generates interrupts on VBLANK.
main: added generic RAM memory operations.
main: replaced all existing RAM memory ops by generic RAM ops.
main: error messages are now printed when memory operations don't lead anywhere.
main: added helper macros useful for defining resources.
main: refactored machine resource definitions.
nes: NROM mapper now supports PPU vertical and horizontal mirroring.
nes: PPU now creates an actual window.
main: fixed compile-time errors regarding anonymous unions (older gcc versions).
nes: added helper macros for cart header access.
main: added default ROM memory ops.
main: introduced new MEM/MEMX macros simplifying memory area definitions.
nes: added CHR region and according cart mapping.