Thanks to Ross, Ben, and the other testers for looking at v505 in detail here!

Hijack v506 is now released, with a substantial rewrite/simplification of the I2C code, reducing duplicated paths and speeding it up quite significantly in general (important, since it runs with interrupts disabled at times).

This probably results in bit-to-bit timings closer to Hugo's original code, way back before I ever began hacking it (years ago), but faster overall due to shorter start sequences.

Cheers