Need a simple installer script

According to the maintainer of the sunxi uboot it is not possible to reliably boot from all devices using the SD card unless you have an uboot specifically made for each device. That would require a specific Linux SD image for each device. That is not a realistic scenario.

So what we need is an installer script that installs the uboot to NAND. No dd commands are needed. Just backup the existing uboot and copy the new one over. Then give the choice of installing the rootfs to SD card, and/or possibly NAND also.

Jeffs existing installer script could easily be adopted to the task.