Now works on Cyclone V too

Thanks to @fritzbauer the design now also works
with QMTech's Cyclone V boards.

Device basically useable

The device is now basically useable and this marks the first real release.

This is an important bugfix release:

• Audio input in Stereo Mode (eg. VoIP/Videoconferencing) works again (#3)

If you find bugs, please file an issue.

Mutual MIDI works!

Both USB devices now can send each other MIDI.
Tested working on EP4CE55 (EP4CE15 should work as well too).
Problems on Cyclone V (DAC audio FIFO overruns, sample rate feedback too high).
Attached bitstream files are for the EP4CE55.
Known Issues:
Audio input has glitches in two channel mode:

USB1 ↔ USB2 bidirectional audio works

Now USB2 ↔ USB1 audio sending/receiving works both ways

Now includes a new ADAT transceiver implementation which
uses a fraction of its resources.

Also included in this release is a USB analyzer trace of USB1 which
is a square LFO going from zero to full. This demonstrates the low latency
of the device of about 0.2ms.

Bitstream files are for the EP4CE55, which I use for development convenience.

Now both headphone DACs on the board work

Both DACs are now operational. Bitstream files are for the EP4CE55 board.
If you need them for the EP4CE15 board, let me know.

All four ADAT transceivers seem to be solid now

The previous version had FIFO overruns when more than two ADAT receivers were plugged in.
I increased the FIFO sizes and now it seems to work well will all receivers active.

The attached bitstreams are for the EP4CE55, which I develop on.
The production version will likely have a pin compatible EP4CE15.

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.