Support new SD card controller

[sy2002]

Here is the QNICE branch which is based on the "M2M branch" V1.61 that includes MJoergen's new SD card controller:
https://github.com/sy2002/QNICE-FPGA/tree/mfj_new_sdcard

MJoergen's new SD controller passed "F+D" in the monitor plus the hardcore testing suite "fwrite.c". Here are his comments taken from a Slack conversation between him and me:

1. My SDCard repo is updated with the latest fixes.
2. The QNICE repo is revived, so that V1.61 standalone builds and works on R3 (with old SD card controller).
3. The QNICE repo has added a branch "mfj_new_sdcard" based off V1.61. Has been tested using your fwrite.c program.
4. The M2M repo has added a branch "mfj_new_sdcard" using this new QNICE. Builds, but has not been tested.
5. The M2M repo needs more work, because we need to support SPI mode on R3. This requires some work, and I'm not motivated for that right now. So I'll leave things as they are now, and go back to the VIC20 repo.
6. As we talked about on our last call, I don't think the new SD card controller is ready for M2M v2.0, partly due to very limited testing, and partly due to lack of support for SPI mode on R3. But the work required is of limited scope, so we might conceivably make a M2M V2.1 in the future, using the new SD card controller.

[sy2002]

Big advantage of doing this:

The sheer speed (on R6 boards) will probably allow us to emulate hard disks for AMIGAs and Atari STs

Disadvantages:

• The complexity it adds for R3 vs R6
• Testing efforts