v2.1.1

Improved GC support, which now works with multiple functions on the stack.

Also includes tweak from @stephen-hansen to read from stdin if no filename is provided, which means code can now be run via:

my-compiler < source.441 | ir441 exec

in addition to the old workflow based on pointing the interpreter at a file (which still works).

This release also includes a native Windows x86-64 binary.

Full Changelog: v2.1...v2.1.1