Add MAX31865
This adds the MAX31865 RTD temperature sensor amplifier. Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX31865.pdf
This adds the SSOP and TQFN versions. They are mostly identical, except:
- Pin numbering is different
- TQFN has an exposed pad connected to GND (represented as a hidden stacked pin in the symbol).
There is one remaining checklib violation:
- Pin SDO (14) @ (-700,200) is type TRISTATE : suggested OUTPUT
However, the SDO pin is a MISO pin that is tristated (to support multiple SPI devices), so TRISTATE is more appropriate.