applet.audio.yamaha_opl: replace ~CS pin with A1. This applet does not really need ~CS, since the chip can be safely always selected. On the other hand, having A0 and A1 allows us to interface almost every OPx device, with the chief exception of OPL4.

applet.program.ice40_sram: Rewrite to use the SPIMaster applet as base Signed-off-by: Sylvain Munaut

applet.interface.spi_master: Set SS even on zero length transfers This allows the host to control the SS state without actually transferring anything Signed-off-by: Sylvain Munaut

applet.interface.spi_master: add omissions from commit 724208f5.

applet.interface.spi_master: let subclasses add their own pin arguments. This makes sense for cases where a subclassing applet e.g. requires SS, SCK, and MOSI but doesn't need MISO at all.

access.direct.multiplexer: inject pin location into bitstream ID. Fixes #103.

cli: fix --rev argument validation.

applet.audio.yamaha_opl: use ClockGen, overclock to 15 MHz.

gateware.clockgen: implement universal clock generator. This replaces gateware.uart.uart_bit_cyc. Fixes #80.

applet.interface.jtag_pinout: try most likely TRST# first. Faster enumeration and less stress on the DUT.