First version with all 4 ADAT terminals works

Although still with bugs,
this is a first version with 32 input and output channels working.
The attached .sof file is for one-time loading of the FPGA.
If you want to flash permanently, write the .jic file with the Quartus Programmer
into the FPGA board.
The current files are built for the EP4CE55 but eventually a
pin-compatible EP4CE15 will be used.