- define CIRCUITPY_BUILD_EXTENSIONS to predefined values
- set CIRCUITPY_BUILD_EXTENSIONS in port and board config
- reuse the support matrix "get_settings_from_makefile" to get it
- move the existing port and board specific values
- remove the C3 specific board values because it's not the default
- update build_release_files.py to use get_settings_from_makefile
Passing in a PWMOut still works but is deprecated. It will be
removed in CircuitPython 8.0.0
This also switches STM32 timer indices and channel indices to
0-based in our pin data rather than `- 1` everywhere. The latter is
more bug prone.
Most of the way for #3264
Tested on Metro M0, Metro M4, Feather S2, Feather nRF52840, Feather
STM32F4 and Arduino RP2040.
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.
Introduces a way to place CircuitPython code and data into
tightly coupled memory (TCM) which is accessible by the CPU in a
single cycle. It also frees up room in the corresponding cache for
intermittent data. Loading from external flash is slow!
The data cache is also now enabled.
Adds support for the iMX RT 1021 chip. Adds three new boards:
* iMX RT 1020 EVK
* iMX RT 1060 EVK
* Teensy 4.0
Related to #2492, #2472 and #2477. Fixes#2475.
