Added a simple AXI interconnect generator.
Refactoring, preparation for axi-based system
Some more axi-bus preparation.
Some more axi-related refactoring.
DNA reader is now axi-based.
Simplified the bus (avakar's axi? aaxi?).
Moved USB mem into aaxi system.
Moved usb to aaxi system.
Moved the sampler into aaxi system, disabled sdram.