* stack decoder
* +x
* cut here
* last alloc explain, line breaks
* capture
* print ctx line
* ...and dont ignore sp
* non-hyphenated arg for elf, toolchain path to bin/
either for when tools are already in PATH
or, using `pio pkg exec --package toolchain-xtensa python decoder.py ...`
(where package is a full version spec for pio registry)
