gateware.boneless: add explicit tests for JUGE and JULT.

cli: add --synthesis-opts, for passing options to Yosys' synth_ice40.

access.direct.demultiplexer: fix TypeError when length is None

software: require libusb1>=1.6.6. At least python-libusb1 1.6.3 (which ships in Debian) has a nasty bug where control reads end up returning all zeroes, for an unknown reason. python-libusb1 1.6.6 works correctly.

arch.boneless: fix typo.

cli: implement `factory --force`.

revC: line up some traces better

revC: another silkscreen tweak near USB connector

applet.selftest: test synthesis.

gateware.boneless: formatting. NFC.