Support pid, port, reference, and identifier types

[yuezato]

Question: which one of the following is the correct definition?

1. sup(TyPid, TyPort) = TyPid | TyPort
2. sup(TyPid, TyPort) = TyIdentifier

[yoshihiro503]

It's OK: sup(TyPid, TyPort) = TyPid | TyPort

[yuezato]

Finally, we decide to let Fialyzer not have the type Identifier internally.

This decision stands on http://erlang.org/doc/reference_manual/typespec.html, which says identifier() is the alias of pid() | port() | reference().

[yoshihiro503]

Add some testing cases like:

-spec foo(pid() | port(), (identifier()) -> ok) -> ok.
foo(P, F) ->
  F(P).

[yuezato]

Add the following BIFs

• [x] self() -> pid() http://erlang.org/doc/man/erlang.html#self-0
• [x] is_process_alive(pid()) -> bool() http://erlang.org/doc/man/erlang.html#is_process_alive-1
• [x] list_to_port(string()) -> port() http://erlang.org/doc/man/erlang.html#list_to_port-1
• [x] port_ot_list(port()) -> string() http://erlang.org/doc/man/erlang.html#port_to_list-1
• [x] unlink(pid() | port()) -> true http://erlang.org/doc/man/erlang.html#unlink-1
• [x] make_ref() -> reference() http://erlang.org/doc/man/erlang.html#make_ref-0
• [x] ref_to_list(reference()) -> string() http://erlang.org/doc/man/erlang.html#ref_to_list-1

Note: list_to_port may throw the exception badarg.