set up parsing structure

We tokenize, and then do the simplest possible recursive descent.

We don't want to evaluate anything, so infix operators are out,
meaning no shunting yard or tree rearranging or LR(1) shenanigans
are necessary, just write the code.

If we want to 'peek', just take the next token, and pass it around
from that point on, until it can actually be consumed.

src/hz_aaci.erl

@@ -22,6 +22,8 @@
          fate_to_erlang/2,
          erlang_args_to_fate/2,
          get_function_signature/2]).
+% Internal stuff that is useful for writing AACI unit tests.
+-export([annotate_type/2]).
 
 %%% Types