New protocol decoder: microwire

Yup, it's time for a new protocol decoder again. libsigrokdecode supports the microwire decoder since a few days.

Microwire is a "serial interface" (like so many others) that was specified by National Semiconductor (now TI) in 1992. The spec (PDF) is publically available.

It's often used in serial EEPROMs such as the 93LC56, 93C66 and various others from many different vendors.

As usual, there are some example files in sigrok-dumps and some test-cases in sigrok-test.

The protocol decoder was contributed by Kevin Redon, thanks a lot!

A higher-level decoder which stacks on top of this one and decodes the 93Cxx EEPROM-specific commands is available as well, more on that later.