With the bus exposed, we can send custom commands to the display, to
leverage advanced features specific to the display, which are not
exposed by default.
This changes a number of things in displayio:
* Introduces BuiltinFont and Glyph so the built in font can be used by libraries. For boards with
a font it is available as board.TERMINAL_FONT. Fixes#1172
* Remove _load_row from Bitmap in favor of bitmap[] access. Index can be x/y tuple or overall index. Fixes#1191
* Add width and height properties to Bitmap.
* Add insert and [] access to Group. Fixes#1518
* Add index param to pop on Group.
* Terminal no longer takes unicode character info. It takes a BuiltinFont instead.
* Fix Terminal's handling of [###D vt100 commands used when up arrowing into repl history.
* Add x and y positions to Group plus scale as well.
* Add bitmap accessor for BuiltinFont
Display rotation is relative to the scan order of the display.
The scan order can be found by scrolling the display with command
0x37 `display_bus.send(0x37, struct.pack(">H", i % 128))`
Fixes#1504
