Change packer to write to/from port directly
Fix define-command/incr so that it actually increments the value by default
Remove commented-out function
Add new IO functions for packer
Add missing import
Add put-u16, put-u32 and put-u64
Have make-packer write directly to the port
Have make-unpacker read directly from a port
Add test suite and runner
Merge branch 'pack-io'