This was never completed and is not used in ESP8266 code.
To implement 3-wire mode for ESP32, it will in any case be better to use
a similar implementation as for ESP8266 with 9-bit hardware SPI.
There is a silicon bug in the ESP32, writing the same value to a
register twice sometimes fails. TFT_CS needs a delay though, so the fix
is to write two different values to the register.
Reference to particular drivers in examples have been removed as
multiple display drivers are now supported.
Tabs replaced by spaces in header file by file editor.
RPi TFT with write strobe SPI clock rate dropped to 20MHz (display
cannot cope with new high rate siWriteBlock() function)
Kristian Nielsen