* Absorb ST7735 support into the generic ST7789 driver and rename to PicoGraphics
* Delete obsolete MicroPython modules
* Refactor PicoGraphics to inherited class for each pen type
* Refactor ST7789 and ST7735 to derive from DisplayDriver
* Allow user to set pen_type in MicroPython constructor for RGB565, RGB332, P8 and P4 modes
* Make ST7789 accept only full config with SPI pins
* Make Generic ST7789 wrapper library handle "slot"
* Update Round LCD and 240x240 Square LCD
* Remove Python Round LCD and 240x240 LCD modules (we need the space!)
* Remove C++ Round LCD and 240x240 LCD libraries (they're a little redundant!)
* Fix garbage collected framebuffer bug in Python ST7789
* Deprecate "flip" in favour of "configure_display"
* Tidy up ST7789, remove dead/unused/commented code
Add the init required for the 320x240 2.0" LCD.
Add an option to set baudrate, 320x240 needs 74MHz for 60FPS
Add library and example for 320x240 2.0 LCD.
* Add a common/pimoroni.hpp to list default pins for various add-ons
* Move the BG SPI Slot enum here for safe keeping
* Switch all GPIO pin references to "uint" to match Pico SDK and bring back PIN_UNUSED as UINT_MAX
A new constructor has been added which accepts a enum type BG_SPI_SLOT which can be either:
ST7789::BG_SPI_FRONT or ST7789::BG_SPI_BACK.
This selects the correct CS/BL pins for the respective breakout-garden SPI slot.
Additionally the PWM'd backlight is turned *on* by default to avoid any confusion when the user does not set a value.