This enables the _stage library and adds stage and ugame modules to the
frozen modules, so that all Stage games should work.
I had to do several hacks:
* Since displayio.release_displays doesn't release the pins, I couldn't
re-initialize the display inside the ugame module. Instead I changed
the default display initialization for the board to match what Stage
expects.
* I wanted to make the MENU key works as K_Z, but when I try to use it
with the keypad module, I get "pin in use" error. So for now only the
A and B buttons are used.
Since Actions passed on the previous commit, where this computed value
was checked against the specified value (if any), this is no net change,
except that we no longer need to specify it for particular boards or
ports.
Restructures the STM port of Circuitpython to be more generic about the STM32 chip lines to support
the F7 and H7 series of chips. Adds the new Packages directory to organize different chip layouts
between lines. Makes general changes to the Makefile to condense board-level flags to the minimum
and support the new chip series. Adds the new chip line to the Peripherals directory, along with
new python tools used to generate peripheral text automatically in the tools/ directory.
