Increase number of 595 chips supported

[MikePinball]

The current configurator supports up to 8 TLC5940 chips which means all 128 output ports are supported.

However only 8 74HC595 chips are available which only gives 64 ports. Can this be increased to a maximum of 16? Or is there a hardware issue for the I/O length? Chime boards might only have one 595 but an regular output board could have 2 or 4 595 chips so the wire length is not so long.

[mjrgh]

I don't think there's any electronics/signalling issue with increasing the limit, as the data rate is so low for these. And I don't think there's any reason the firmware can't handle it, so it should be feasible. It would be good to test it out and make sure there isn't some subtlety I'm missing, just in case - if you want to try that, let me know what you find.