Kurt Eckhardt fc9159a681 T4.1 make SPI CS pins be index not mask, plus Franks change to timing The CS pins on T4.x are not like 3.x in that is you select one by index, not one or more by mask. So changed returned values to be index (1 based) Also while testing I pulled in Frank's change for adding delay after CS pin is logically selected.		4 lat temu
examples	Example setup code bug	7 lat temu
README.md	Update readme	10 lat temu
SPI.cpp	T4.1 make SPI CS pins be index not mask, plus Franks change to timing	4 lat temu
SPI.h	T4.1 make SPI CS pins be index not mask, plus Franks change to timing	4 lat temu
keywords.txt	Add SPI Buffer functions	7 lat temu
library.properties	Add library.properties	8 lat temu

SPI Library for Teensy