Added support for ILI9331

[monte-monte]

I have a round display based on ILI9331 controller. They are sold on aliexpress and can be easily found by "ILI9331" query. There is no support for them in any graphics library for arduino. The closest in terms of support is MCFRIEND_kbv library, which lacks init code for ILI9331, but has all other commands and registers sorted out.
So with help of a datasheet, sample init code from a seller and MCUFRIEND_kbv library I've made it work. I'm not sure how many other displays with this type of controller are there, but I would be pleased if I've found it was supported when I bought one.
I also had to add writeC16D16 function to Arduino_DataBus class as this controller requires 16 bit writes for both the register and data.

I've recorded a video of this display running your PDQgraphicstest example sketch. I've added invertDisplay and displayOff/On function in the end to show them working.
This display has only 8/16 bit parallel interface, though controller supports SPI too.

VID_20220120_135124.mp4

[moononournation]

After seeing your video, I think you should:

• Align all display rotation orientation with display FPC #46 Align display rotation orientation with display FPC at 6 o'clock
• adjust the margin like ST7789

Arduino_GFX *gfx = new Arduino_ST7789(bus, 7 /* RST */, 0 /* rotation */, true /* IPS */,
    240 /* width */, 240 /* height */, 0 /* col offset 1 */, 80 /* row offset 1 */);

• upload adjusted video to Youtube, I will share the link at README.md

[monte-monte]

Rotation is correct, I just forgot to change rotation in sketch, I filmed it being set to 2.
https://youtu.be/XLWVXRWZODg

[moononournation]

please give me a Youtube link if you have uploaded your video

[monte-monte]

@moononournation don't you see it in my last comment?