Interlaced 640x480 with more test image improvements (#3)

Changes:
- Interlacing without interrupts
- Added dim hue bars on the test image
- Keep frame buffer 1 untouched, use fb2

Notes:
- Since the test image is still, use Weave deinterlacing.
- There is a weird phenomena where the busy bit of the RDP
  goes false but data continues to be written to the frame
  buffer, resulting in artifacts. This is worked around by
  drawing the CPU content again after a second frame swap.
  More investigation is needed.