applet.sensor.hx711: new applet.

cli: flush demultiplexer after each command in run-repl. This avoids an absurdly infuriating situation where, if you send commands to DUT but do not read anything back, they won't actually get delivered until the buffer is full enough, which is often after several minutes of frustrated debugging. I think I got bitten by this every single time I tried to use run-repl.

applet.interface.{i2c_initiator,uart}: remove obsolete repl command. These weren't customized, so run-repl is a complete replacement.

applet.interface.jtag_probe: fix typo.

revC schematics: fix recommended LVDS connector Fixes #172

protocol.jesd3: accept tabs as whitespace as well.

protocol.jtag_svf: fix lexing of reals with more than 1 integral digit. Before this commit, a real like `50021E-6` would be parsed as an integer `5002` and a real `1E-6`.

Switch to upstream nMigen.

gateware.analyzer: disable broken FIFO tests. See issue #182.

test: add script to run tests. `python setup.py test` is apparently deprecated. This reuses some of the internal implementation of that command, but at least establishes a stable interface to run the tests with.