Neither collect_tag_ctors nor the second pass in collect_items needed
to be separate passes.

Also remove obsolete obj_methods table kludge.

This makes it clearer that it's only valid for local nodes.

Extern interfaces still don't get recognized.

Issue #1227

Issue #1227

Closes #1399

The tutorial should mention the ++ arg passing style

this will address the (crashing) new test added.

It contains a vector, which shouldn't be copied all the time.

On second thought, re-land pull request #1385 with backquotes; easier to grep, can change in the future.

Use singlequotes in the typechecker error messages too, to distinguish code and English

misc standard library additions

The AST no longer references it.

Issue #1227

This parallels nicely with string_reader and string_writer, but
working with raw byte strings. I'm not quite sure if the return
type for bytes_writer.get_bytes should be [u8] or [mutable u8]
though, so I'm arbitrarily picking mutable for now.