src: Use UnicodeError instead of UnicodeDecodeError ...

MicroPython doesn't support UnicodeDecodeError, just UnicodeError.

main: Use new parser if NEWLANG_NEW_PARSE is set ...

This is not intended to be actually used outside testing compatibility
with micropython as we don't actually have tests on it yet.

main: Put executable name in usage

main: Add run_file function for REPL use ...

This should help using NewLang from micropython.

log: Rely on main for the getenv call ...

micropython on the Pi Pico for some reason doesn't support getenv, so
try and push this in to main where we can decide to use it.

main: Remove unused nowait_main function

port: Add micropython-compatible atexit wrapper

run: Use run.py to run src/main.py ...

This completely removes the weird logic for editing paths at the expense
of some more code.

main: Fix spacing

main: Add a main function that waits ...

This is enabled in the zipapp to make life easier when the program is
run from a GUI.

parse: Move to oldparse ...

This is in preparation of writing a new parser.
Once the new parser is ready then this code can be junked.

Change license to LGPL-2.1-only

src: Put repo directory in path so it can find the src module ...

This was also broken when moving things to use 'src' as the module name.

Fixes: 06c8537

Add test harness and simple fuzz test

make: Add way to build NewLang executable

src: Reformat using black

Restructure files