Removes i2c_inst_t from constructors since it's ignored, and updated the Python bindings not to supply this argument. Instance is inferred from the supplied pins.
Removes all driver-specific SDA/SCL pin definitions and defaults.
Pin type is "uint" everywhere, but "PIN_UNUSED" is *int*_max for MicroPython compat. That's still a lot of pins!
Adds baudrate to the I2C class, and allows a driver (like Trackball) to check the baudrate is supported
This change adds a common I2C class, gathering various I2C functions into a single point of responsibility.
It's necessary for correctly managing the I2C bus pins and state across multiple devices.
* Add a common/pimoroni.hpp to list default pins for various add-ons
* Move the BG SPI Slot enum here for safe keeping
* Switch all GPIO pin references to "uint" to match Pico SDK and bring back PIN_UNUSED as UINT_MAX
Phil Howard
ZodiusInfuser
Jonathan Williamson