To program SPI Flash and restart FPGA

[jackgassett]

This commit, when used with harbaum/FPGA-Companion#30, can program a new bitfile into flash and restart the FPGA to the new bitfile.

Remember to set up multiboot:

[vossstef]

Hi @jackgassett , i added your feature as compile feature for the Tang Primer 20k board.
You need to set in the ESP32PRG : integer := 0 -- 0:no, 1:yes
to 1, set the multiboot address and recompile. Hope that it helps you in the special esp32 firmware development.
If you think that the additions i integrated from your pull are correct and do what you intended then pls. close your MR.

My VIC20 and C64 cores are at the moment needing the m0s(5), m0s(6) and m0s(7) plus the flash locations for storing the DOS and Kernal ROMs and would be blocked by a general FPGA Companion flash programmer for all cores.