Added Inkplate boards

[nitko12]

Hi, what's the procedure for adding boards to platform, is a PR here enough?

I'll be publishing a library soon hopefully :)

[rafaelmagu]

Any updates on this?

[johndbritton]

I was able to use these definitions in my project by dropping them in the boards directory, but it'd be nice for this to get merged. @valeros Does this need something more?

[valeros]

It's highly desirable that these boards are added to the official Arduino core for ESP32 https://github.com/espressif/arduino-esp32 with proper variant files.

[SyntaxColoring]

Is -DARDUINO_INKPLATE6COLOR correct, or should it be -DARDUINO_INKPLATECOLOR (without the 6)?

The Arduino examples all check for the define without the 6.

https://github.com/SolderedElectronics/Inkplate-Arduino-library/blob/3f1908e3cda550b156e3e5b8adeb41177a456f9e/examples/Inkplate6COLOR/Basic/Inkplate6COLOR_Full_Screen_Colors/Inkplate6COLOR_Full_Screen_Colors.ino#L16

I also can't find any reference to the define with the 6 in Inkplate-Arduino-Library, whereas it references the one without the 6 a bunch.

https://github.com/SolderedElectronics/Inkplate-Arduino-library/blob/3f1908e3cda550b156e3e5b8adeb41177a456f9e/src/Inkplate.h#L124